Annual report pursuant to Section 13 and 15(d)

Information by Business Segment (Details 3)

v2.4.1.9
Information by Business Segment (Details 3) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Reconciliation of segment assets to total assets      
Assets $ 3,670,257us-gaap_Assets $ 3,629,952us-gaap_Assets  
Segment assets      
Reconciliation of segment assets to total assets      
Assets 2,951,495us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_OperatingSegmentsMember
2,905,630us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_OperatingSegmentsMember
2,945,930us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_OperatingSegmentsMember
Non-operating property assets      
Reconciliation of segment assets to total assets      
Assets 567,586us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_NonOperatingPropertyAssetsMember
517,564us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= ofc_NonOperatingPropertyAssetsMember
 
Other assets      
Reconciliation of segment assets to total assets      
Assets $ 151,176us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember
$ 206,758us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= us-gaap_MaterialReconcilingItemsMember