COPT Defense Properties Annual report pursuant to Section 13 and 15(d)

Information by Business Segment (Details)

Information by Business Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment financial information for real estate operations
Revenues from real estate operations	$ 519,068	$ 479,711	$ 498,633
Property operating expenses	194,488	179,799	180,704
NOI from real estate operations	324,580	299,912	317,929
Segment assets	3,909,312	3,664,236
Operating Segments [Member]
Segment financial information for real estate operations
Revenues from real estate operations	519,068	479,711	498,633
Property operating expenses	194,488	179,799	180,704
NOI from real estate operations	324,580	299,912	317,929
Additions to long-lived assets	335,269	64,601	56,877
Transfers from non-operating properties	307,120	141,899	264,290
Segment assets	3,265,469	2,951,495	2,905,630
Operating Segments [Member] \| Defense/Information Technology Sector [Member]
Segment financial information for real estate operations
Revenues from real estate operations	394,283	376,742	385,863
Property operating expenses	144,444	137,486	135,906
NOI from real estate operations	249,839	239,256	249,957
Additions to long-lived assets	130,670	45,379	42,244
Transfers from non-operating properties	194,647	121,227	161,301
Segment assets	2,342,746	2,188,021	2,107,793
Operating Segments [Member] \| Defense/Information Technology Sector [Member] \| Fort Meade/BW Corridor [Member]
Segment financial information for real estate operations
Revenues from real estate operations	244,274	233,764	234,857
Property operating expenses	83,309	80,824	80,149
NOI from real estate operations	160,965	152,940	154,708
Additions to long-lived assets	31,883	24,173	28,009
Transfers from non-operating properties	45,560	56,699	50,067
Segment assets	1,290,028	1,264,353	1,229,192
Operating Segments [Member] \| Defense/Information Technology Sector [Member] \| Northern Virginia Defense/IT [Member]
Segment financial information for real estate operations
Revenues from real estate operations	49,199	48,313	56,524
Property operating expenses	20,107	19,071	19,718
NOI from real estate operations	29,092	29,242	36,806
Additions to long-lived assets	90,248	7,119	5,522
Transfers from non-operating properties	50,690	360	37,234
Segment assets	411,196	372,041	385,061
Operating Segments [Member] \| Defense/Information Technology Sector [Member] \| Lackland Air Force Base [Member]
Segment financial information for real estate operations
Revenues from real estate operations	39,659	34,463	31,252
Property operating expenses	22,004	19,677	16,784
NOI from real estate operations	17,655	14,786	14,468
Additions to long-lived assets	0	0	5
Transfers from non-operating properties	32,307	0	0
Segment assets	134,381	102,232	103,650
Operating Segments [Member] \| Defense/Information Technology Sector [Member] \| Navy Support Locations [Member]
Segment financial information for real estate operations
Revenues from real estate operations	28,177	31,335	33,431
Property operating expenses	13,229	12,576	12,872
NOI from real estate operations	14,948	18,759	20,559
Additions to long-lived assets	7,656	10,010	4,945
Transfers from non-operating properties	1,408	0	14
Segment assets	196,090	195,972	195,105
Operating Segments [Member] \| Defense/Information Technology Sector [Member] \| Redstone Arsenal [Member]
Segment financial information for real estate operations
Revenues from real estate operations	11,228	10,446	5,050
Property operating expenses	3,497	3,066	1,282
NOI from real estate operations	7,731	7,380	3,768
Additions to long-lived assets	883	4,077	3,563
Transfers from non-operating properties	13,190	21,014	48,799
Segment assets	108,038	97,209	77,773
Operating Segments [Member] \| Defense/Information Technology Sector [Member] \| Colorado Defense / IT [Member]
Segment financial information for real estate operations
Revenues from real estate operations	0	0	12,229
Property operating expenses	0	0	3,797
NOI from real estate operations	0	0	8,432
Additions to long-lived assets	0	0	200
Transfers from non-operating properties	0	0	987
Segment assets	0	0	0
Operating Segments [Member] \| Defense/Information Technology Sector [Member] \| Data Center Shells [Member]
Segment financial information for real estate operations
Revenues from real estate operations	21,746	18,421	12,520
Property operating expenses	2,298	2,272	1,304
NOI from real estate operations	19,448	16,149	11,216
Additions to long-lived assets	0	0	0
Transfers from non-operating properties	51,492	43,154	24,200
Segment assets	203,013	156,214	117,012
Operating Segments [Member] \| Regional Office [Member]
Segment financial information for real estate operations
Revenues from real estate operations	98,165	85,025	98,487
Property operating expenses	36,165	31,427	35,488
NOI from real estate operations	62,000	53,598	62,999
Additions to long-lived assets	204,139	19,290	13,244
Transfers from non-operating properties	22,313	17,942	32,692
Segment assets	608,471	526,988	556,718
Operating Segments [Member] \| Operating Wholesale Data Center [Member]
Segment financial information for real estate operations
Revenues from real estate operations	19,032	10,430	7,271
Property operating expenses	10,402	7,286	6,360
NOI from real estate operations	8,630	3,144	911
Additions to long-lived assets	132	22	598
Transfers from non-operating properties	89,745	1,108	70,106
Segment assets	243,338	163,177	166,790
Operating Segments [Member] \| Other Segments [Member]
Segment financial information for real estate operations
Revenues from real estate operations	7,588	7,514	7,012
Property operating expenses	3,477	3,600	2,950
NOI from real estate operations	4,111	3,914	4,062
Additions to long-lived assets	328	(90)	791
Transfers from non-operating properties	415	1,622	191
Segment assets	$ 70,914	$ 73,309	$ 74,329