Annual report pursuant to Section 13 and 15(d)

Investing Receivables (Details)

v2.4.1.9
Investing Receivables (Details) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Investing receivables 52,147us-gaap_NotesReceivableNet $ 53,663us-gaap_NotesReceivableNet
Notes receivable from City of Huntsville    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Investing receivables 49,147us-gaap_NotesReceivableNet
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= ofc_NotesReceivableFromCityOfHuntsvilleMember
44,055us-gaap_NotesReceivableNet
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= ofc_NotesReceivableFromCityOfHuntsvilleMember
Notes receivable from City of Huntsville | LW Redstone Company, LLC    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Stated interest rate (as a percent) 9.95%ofc_NoteReceivableTermsInterestRate
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= ofc_NotesReceivableFromCityOfHuntsvilleMember
/ dei_LegalEntityAxis
= ofc_LwRedstoneCompanyLlcMember
 
Debt instrument, term 30 years  
Other investing loans receivable    
Accounts, Notes, Loans and Financing Receivable [Line Items]    
Investing receivables 3,000us-gaap_NotesReceivableNet
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= us-gaap_LoansAndFinanceReceivablesMember
$ 9,608us-gaap_NotesReceivableNet
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= us-gaap_LoansAndFinanceReceivablesMember