Annual report pursuant to Section 13 and 15(d)

Debt (Details 4)

v3.6.0.2
Debt (Details 4)
 1 Months Ended 12 Months Ended
Dec. 28, 2016
USD ($)
Dec. 17, 2015
USD ($)
Aug. 28, 2015
USD ($)
Jun. 29, 2015
USD ($)
May 06, 2015
USD ($)
extension
May 14, 2014
USD ($)
Feb. 14, 2012
USD ($)
Dec. 31, 2014
USD ($)
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Dec. 31, 2014
USD ($)
Debt Instrument [Line Items]                      
(Loss) gain on early extinguishment of debt                 $ 1,110,000 $ (85,275,000) $ 9,552,000
Term Credit Facility Effective February 2012 [Member]                      
Debt Instrument [Line Items]                      
Initial amount borrowed             $ 250,000,000        
Term Credit Facility Effective August 2012 [Member]                      
Debt Instrument [Line Items]                      
Repayments of debt                 120,000,000    
Term Credit Facility Effective September 2011 [Member]                      
Debt Instrument [Line Items]                      
Repayments of debt                   150,000,000 $ 100,000,000
Fixed rate mortgage loans [Member]                      
Debt Instrument [Line Items]                      
Debt settled through the surrender of real estate assets     $ 150,000,000                
Minimum [Member] | Term Credit Facility Effective February 2012 [Member] | London Interbank Offered Rate (LIBOR) [Member]                      
Debt Instrument [Line Items]                      
Variable rate, spread (as a percent)         0.90%            
Maximum [Member] | Term Credit Facility Effective February 2012 [Member] | London Interbank Offered Rate (LIBOR) [Member]                      
Debt Instrument [Line Items]                      
Variable rate, spread (as a percent)         1.85%            
Secured Loans Due November 2015 And January 2016 [Member]                      
Debt Instrument [Line Items]                      
(Loss) gain on early extinguishment of debt               $ 9,100,000      
Secured Loan Due November 2015 [Member]                      
Debt Instrument [Line Items]                      
Stated interest rate (as a percent)               5.53%     5.53%
Amount of loans repaid upon entry into Revolving Credit Facility and Term Loan Agreement               $ 103,000,000      
Secured Loan Due January 2016 [Member]                      
Debt Instrument [Line Items]                      
Stated interest rate (as a percent)               5.56%     5.56%
Amount of loans repaid upon entry into Revolving Credit Facility and Term Loan Agreement               $ 108,500,000      
Revolving Credit Facility [Member] | Revolving Credit Facility [Member]                      
Debt Instrument [Line Items]                      
Maximum availability                 800,000,000    
Expansion right, maximum borrowing capacity                 $ 1,300,000,000    
Amount available as a percentage of unencumbered Asset value                 60.00%    
Line of credit facility, extension fee percentage                 0.075%    
Weighted average borrowings                 $ 90,300,000 $ 125,000,000  
Weighted average interest rate (as a percent)                 1.64% 1.40%  
Line of Credit [Member] | Term Credit Facility Effective February 2012 [Member]                      
Debt Instrument [Line Items]                      
Maximum availability         $ 300,000,000            
Increase to maximum borrowing capacity         200,000,000            
Aggregate maximum borrowing capacity         $ 500,000,000            
Line of Credit [Member] | Revolving Credit Facility [Member]                      
Debt Instrument [Line Items]                      
Number of extensions | extension         2            
Extension option period (in years)         6 months            
Line of Credit [Member] | Revolving Credit Facility [Member] | Minimum [Member]                      
Debt Instrument [Line Items]                      
Commitment fee percentage         0.125%            
Line of Credit [Member] | Revolving Credit Facility [Member] | Minimum [Member] | London Interbank Offered Rate (LIBOR) [Member]                      
Debt Instrument [Line Items]                      
Variable rate, spread (as a percent)         0.875%            
Line of Credit [Member] | Revolving Credit Facility [Member] | Maximum [Member]                      
Debt Instrument [Line Items]                      
Commitment fee percentage         0.30%            
Line of Credit [Member] | Revolving Credit Facility [Member] | Maximum [Member] | London Interbank Offered Rate (LIBOR) [Member]                      
Debt Instrument [Line Items]                      
Variable rate, spread (as a percent)         1.60%            
Unsecured Debt [Member] | Term Credit Facility Effective December 2015 [Member]                      
Debt Instrument [Line Items]                      
Maximum availability   $ 250,000,000                  
Remaining borrowing capacity                 $ 150,000,000    
Initial amount borrowed   $ 100,000,000                  
Unsecured Debt [Member] | Term Credit Facility Effective December 2016 [Member]                      
Debt Instrument [Line Items]                      
Initial amount borrowed $ 150,000,000                    
Unsecured Debt [Member] | Minimum [Member] | Term Credit Facility Effective December 2015 [Member] | London Interbank Offered Rate (LIBOR) [Member]                      
Debt Instrument [Line Items]                      
Variable rate, spread (as a percent)   1.40%                  
Unsecured Debt [Member] | Maximum [Member] | Term Credit Facility Effective December 2015 [Member] | London Interbank Offered Rate (LIBOR) [Member]                      
Debt Instrument [Line Items]                      
Variable rate, spread (as a percent)   2.35%                  
Senior Notes [Member]                      
Debt Instrument [Line Items]                      
Redemption price (percent)                 100.00%    
Senior Notes [Member] | 5.0% Senior Notes [Member]                      
Debt Instrument [Line Items]                      
Loan amount       $ 300,000,000              
Stated interest rate (as a percent)       5.00%         5.00%    
Debt issuance as a percentage of principal amount       99.51%              
Unamortized discount included in carrying value                 $ 3,000,000 $ 3,300,000  
Interest rate on debt (as a percent)                 5.15%    
Proceeds from debt, net       $ 296,600,000              
Senior Notes [Member] | 5.0% Senior Notes [Member] | Adjusted Treasury [Member]                      
Debt Instrument [Line Items]                      
Basis points used in determining redemption price prior to maturity                 0.45%    
Senior Notes [Member] | 3.70% Senior Notes [Member]                      
Debt Instrument [Line Items]                      
Initial amount borrowed           $ 297,300,000          
Loan amount                 $ 300,000,000    
Stated interest rate (as a percent)           3.70%     3.70%    
Debt issuance as a percentage of principal amount           99.739%          
Unamortized discount included in carrying value                 $ 1,700,000 2,100,000  
Interest rate on debt (as a percent)                 3.85%    
Senior Notes [Member] | 3.70% Senior Notes [Member] | Adjusted Treasury [Member]                      
Debt Instrument [Line Items]                      
Basis points used in determining redemption price prior to maturity                 0.25%    
Senior Notes [Member] | 3.60% Senior Notes [Member]                      
Debt Instrument [Line Items]                      
Stated interest rate (as a percent)                 3.60%    
Unamortized discount included in carrying value                 $ 2,000,000 2,200,000  
Interest rate on debt (as a percent)                 3.70%    
Senior Notes [Member] | 3.60% Senior Notes [Member] | Adjusted Treasury [Member]                      
Debt Instrument [Line Items]                      
Basis points used in determining redemption price prior to maturity                 0.30%    
Senior Notes [Member] | 5.250% Senior Notes [Member]                      
Debt Instrument [Line Items]                      
Stated interest rate (as a percent)                 5.25%    
Unamortized discount included in carrying value                 $ 3,400,000 $ 3,800,000  
Interest rate on debt (as a percent)                 5.49%    
Senior Notes [Member] | 5.250% Senior Notes [Member] | Adjusted Treasury [Member]                      
Debt Instrument [Line Items]                      
Basis points used in determining redemption price prior to maturity                 0.40%    
Operating properties, net [Member] | 15000 and 15010 Conference Center Drive [Member]                      
Debt Instrument [Line Items]                      
(Loss) gain on early extinguishment of debt     (84,800,000)                
Debt settled through the surrender of real estate assets     $ 150,000,000