Operating Leases (Details) $ in Thousands  | 
 Dec. 31, 2016  
USD ($) 
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| Gross minimum future rentals | |
| 2017 | $ 356,982 | 
| 2018 | 295,727 | 
| 2019 | 247,671 | 
| 2020 | 185,018 | 
| 2021 | 142,114 | 
| Thereafter | 359,001 | 
| Total | $ 1,586,513 | 
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- Definition Future minimum rental payments in aggregate as of the balance sheet date under operating leases. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- References No definition available. 
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- Definition Future rental payments receivable within one year of the balance sheet date under an operating lease. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Future rental payments receivable within the fifth year from the balance sheet date under an operating lease. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Future rental payments receivable within the fourth year from the balance sheet date under an operating lease. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Future rental payments receivable within the third year from the balance sheet date under an operating lease. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Future rental payments receivable within the second year from the balance sheet date under an operating lease. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition Future minimum lease payments receivable under operating leases for periods greater than five years following the balance sheet date. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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