Information by Business Segment (Details) - USD ($)
$ in Thousands |
12 Months Ended |
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
| Segment financial information for real estate operations |
|
|
|
| Revenues from real estate operations |
$ 509,980
|
$ 525,964
|
$ 519,068
|
| Property operating expenses |
(190,964)
|
(197,530)
|
(194,488)
|
| UJV NOI allocable to COPT |
5,188
|
2,305
|
0
|
| NOI from real estate operations |
324,204
|
330,739
|
324,580
|
| Additions to long-lived assets |
73,341
|
70,324
|
335,269
|
| Transfers from non-operating properties |
202,211
|
184,640
|
307,120
|
| Segment assets |
3,578,484
|
3,780,885
|
|
| Defense/Information Technology Sector [Member] |
|
|
|
| Segment financial information for real estate operations |
|
|
|
| Revenues from real estate operations |
408,122
|
406,210
|
394,283
|
| Property operating expenses |
(146,558)
|
(148,705)
|
(144,444)
|
| UJV NOI allocable to COPT |
5,188
|
2,305
|
|
| NOI from real estate operations |
266,752
|
259,810
|
249,839
|
| Additions to long-lived assets |
44,352
|
57,131
|
130,670
|
| Transfers from non-operating properties |
202,185
|
184,943
|
194,647
|
| Defense/Information Technology Sector [Member] | Fort Meade/BW Corridor [Member] |
|
|
|
| Segment financial information for real estate operations |
|
|
|
| Revenues from real estate operations |
245,613
|
245,354
|
244,274
|
| Property operating expenses |
(80,697)
|
(83,684)
|
(83,309)
|
| UJV NOI allocable to COPT |
0
|
0
|
|
| NOI from real estate operations |
164,916
|
161,670
|
160,965
|
| Additions to long-lived assets |
26,659
|
26,267
|
31,883
|
| Transfers from non-operating properties |
43,370
|
49,937
|
45,560
|
| Defense/Information Technology Sector [Member] | Northern Virginia Defense/IT [Member] |
|
|
|
| Segment financial information for real estate operations |
|
|
|
| Revenues from real estate operations |
47,118
|
48,964
|
49,199
|
| Property operating expenses |
(16,938)
|
(17,824)
|
(20,107)
|
| UJV NOI allocable to COPT |
0
|
0
|
|
| NOI from real estate operations |
30,180
|
31,140
|
29,092
|
| Additions to long-lived assets |
8,115
|
17,344
|
90,248
|
| Transfers from non-operating properties |
48,328
|
28,230
|
50,690
|
| Defense/Information Technology Sector [Member] | Lackland Air Force Base [Member] |
|
|
|
| Segment financial information for real estate operations |
|
|
|
| Revenues from real estate operations |
47,209
|
46,803
|
39,659
|
| Property operating expenses |
(27,812)
|
(27,357)
|
(22,004)
|
| UJV NOI allocable to COPT |
0
|
0
|
|
| NOI from real estate operations |
19,397
|
19,446
|
17,655
|
| Additions to long-lived assets |
71
|
0
|
0
|
| Transfers from non-operating properties |
0
|
240
|
32,307
|
| Defense/Information Technology Sector [Member] | Navy Support Locations [Member] |
|
|
|
| Segment financial information for real estate operations |
|
|
|
| Revenues from real estate operations |
29,540
|
28,197
|
28,177
|
| Property operating expenses |
(12,619)
|
(12,690)
|
(13,229)
|
| UJV NOI allocable to COPT |
0
|
0
|
|
| NOI from real estate operations |
16,921
|
15,507
|
14,948
|
| Additions to long-lived assets |
8,451
|
9,168
|
7,656
|
| Transfers from non-operating properties |
474
|
0
|
1,408
|
| Defense/Information Technology Sector [Member] | Redstone Arsenal [Member] |
|
|
|
| Segment financial information for real estate operations |
|
|
|
| Revenues from real estate operations |
14,322
|
13,056
|
11,228
|
| Property operating expenses |
(5,783)
|
(4,476)
|
(3,497)
|
| UJV NOI allocable to COPT |
0
|
0
|
|
| NOI from real estate operations |
8,539
|
8,580
|
7,731
|
| Additions to long-lived assets |
1,056
|
4,352
|
883
|
| Transfers from non-operating properties |
2,159
|
3,169
|
13,190
|
| Defense/Information Technology Sector [Member] | Data Center Shells [Member] |
|
|
|
| Segment financial information for real estate operations |
|
|
|
| Revenues from real estate operations |
24,320
|
23,836
|
21,746
|
| Property operating expenses |
(2,709)
|
(2,674)
|
(2,298)
|
| UJV NOI allocable to COPT |
5,188
|
2,305
|
|
| NOI from real estate operations |
26,799
|
23,467
|
19,448
|
| Additions to long-lived assets |
0
|
0
|
0
|
| Transfers from non-operating properties |
107,854
|
103,367
|
51,492
|
| Regional Office [Member] |
|
|
|
| Segment financial information for real estate operations |
|
|
|
| Revenues from real estate operations |
68,262
|
85,805
|
98,165
|
| Property operating expenses |
(28,982)
|
(34,095)
|
(36,165)
|
| UJV NOI allocable to COPT |
0
|
0
|
|
| NOI from real estate operations |
39,280
|
51,710
|
62,000
|
| Additions to long-lived assets |
25,299
|
12,559
|
204,139
|
| Transfers from non-operating properties |
0
|
82
|
22,313
|
| Operating wholesale data centers [Member] |
|
|
|
| Segment financial information for real estate operations |
|
|
|
| Revenues from real estate operations |
28,875
|
26,869
|
19,032
|
| Property operating expenses |
(13,551)
|
(11,512)
|
(10,402)
|
| UJV NOI allocable to COPT |
0
|
0
|
|
| NOI from real estate operations |
15,324
|
15,357
|
8,630
|
| Additions to long-lived assets |
3,580
|
299
|
132
|
| Transfers from non-operating properties |
8
|
(377)
|
89,745
|
| Other [Member] |
|
|
|
| Segment financial information for real estate operations |
|
|
|
| Revenues from real estate operations |
4,721
|
7,080
|
7,588
|
| Property operating expenses |
(1,873)
|
(3,218)
|
(3,477)
|
| UJV NOI allocable to COPT |
0
|
0
|
|
| NOI from real estate operations |
2,848
|
3,862
|
4,111
|
| Additions to long-lived assets |
110
|
335
|
328
|
| Transfers from non-operating properties |
18
|
(8)
|
415
|
| Segment assets [Member] |
|
|
|
| Segment financial information for real estate operations |
|
|
|
| Segment assets |
3,011,284
|
3,004,247
|
3,265,469
|
| Segment assets [Member] | Defense/Information Technology Sector [Member] |
|
|
|
| Segment financial information for real estate operations |
|
|
|
| Segment assets |
2,382,268
|
2,308,189
|
2,342,746
|
| Segment assets [Member] | Defense/Information Technology Sector [Member] | Fort Meade/BW Corridor [Member] |
|
|
|
| Segment financial information for real estate operations |
|
|
|
| Segment assets |
1,263,567
|
1,255,230
|
1,290,028
|
| Segment assets [Member] | Defense/Information Technology Sector [Member] | Northern Virginia Defense/IT [Member] |
|
|
|
| Segment financial information for real estate operations |
|
|
|
| Segment assets |
402,076
|
404,438
|
411,196
|
| Segment assets [Member] | Defense/Information Technology Sector [Member] | Lackland Air Force Base [Member] |
|
|
|
| Segment financial information for real estate operations |
|
|
|
| Segment assets |
128,755
|
131,957
|
134,381
|
| Segment assets [Member] | Defense/Information Technology Sector [Member] | Navy Support Locations [Member] |
|
|
|
| Segment financial information for real estate operations |
|
|
|
| Segment assets |
194,476
|
196,486
|
196,090
|
| Segment assets [Member] | Defense/Information Technology Sector [Member] | Redstone Arsenal [Member] |
|
|
|
| Segment financial information for real estate operations |
|
|
|
| Segment assets |
108,119
|
110,395
|
108,038
|
| Segment assets [Member] | Defense/Information Technology Sector [Member] | Data Center Shells [Member] |
|
|
|
| Segment financial information for real estate operations |
|
|
|
| Segment assets |
285,275
|
209,683
|
203,013
|
| Segment assets [Member] | Regional Office [Member] |
|
|
|
| Segment financial information for real estate operations |
|
|
|
| Segment assets |
400,512
|
442,811
|
608,471
|
| Segment assets [Member] | Operating wholesale data centers [Member] |
|
|
|
| Segment financial information for real estate operations |
|
|
|
| Segment assets |
224,422
|
231,954
|
243,338
|
| Segment assets [Member] | Other [Member] |
|
|
|
| Segment financial information for real estate operations |
|
|
|
| Segment assets |
$ 4,082
|
$ 21,293
|
$ 70,914
|