Schedule III - Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	652,209
Initial Costs
Land	1,057,802
Buildings & Improvements	2,791,443
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	4,497,016
Total Costs
Land	1,057,802
Buildings & Improvements	7,288,459
Total	8,346,261	[1]
Accumulated Depreciation	(1,120,245)	[2]	(952,106)	(875,035)	(742,535)
Net Cost Basis	7,226,016
Secured notes payable	652,209		708,831
Area of Real Estate Property	18,729,282
Alexandria Center at Kendall Square
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	106,093
Initial Costs
Land	280,713
Buildings & Improvements	199,583
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	662,031
Total Costs
Land	280,713
Buildings & Improvements	861,614
Total	1,142,327	[1]
Accumulated Depreciation	(44,490)	[2]
Net Cost Basis	1,097,837
Alexandria Technology Square®
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	0
Buildings & Improvements	619,658
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	186,472
Total Costs
Land	0
Buildings & Improvements	806,130
Total	806,130	[1]
Accumulated Depreciation	(141,360)	[2]
Net Cost Basis	664,770
480 Arsenal Street
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	6,413
Buildings & Improvements	5,457
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	46,115
Total Costs
Land	6,413
Buildings & Improvements	51,572
Total	57,985	[1]
Accumulated Depreciation	(14,358)	[2]
Net Cost Basis	43,627
780/790 Memorial Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	0
Buildings & Improvements	0
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	45,140
Total Costs
Land	0
Buildings & Improvements	45,140
Total	45,140	[1]
Accumulated Depreciation	(17,895)	[2]
Net Cost Basis	27,245
500 Arsenal Street
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	3,360
Buildings & Improvements	7,316
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	29,136
Total Costs
Land	3,360
Buildings & Improvements	36,452
Total	39,812	[1]
Accumulated Depreciation	(13,368)	[2]
Net Cost Basis	26,444
167 Sidney Street/99 Erie Street
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	0
Buildings & Improvements	12,613
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	12,273
Total Costs
Land	0
Buildings & Improvements	24,886
Total	24,886	[1]
Accumulated Depreciation	(4,064)	[2]
Net Cost Basis	20,822
79/96 Thirteenth Street Charlestown Navy Yard
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	4,556	[3]
Initial Costs
Land	0
Buildings & Improvements	6,247
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	8,661
Total Costs
Land	0
Buildings & Improvements	14,908
Total	14,908	[1]
Accumulated Depreciation	(2,785)	[2]
Net Cost Basis	12,123
Alexandria Park at 128
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	23,301	[3],[4]
Initial Costs
Land	10,439
Buildings & Improvements	41,596
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	56,059
Total Costs
Land	10,439
Buildings & Improvements	97,655
Total	108,094	[1]
Accumulated Depreciation	(27,003)	[2]
Net Cost Basis	81,091
225 Second Avenue
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	2,925
Buildings & Improvements	14,913
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	17,047
Total Costs
Land	2,925
Buildings & Improvements	31,960
Total	34,885	[1]
Accumulated Depreciation	0	[2]
Net Cost Basis	34,885
19 Presidential Way
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	12,833
Buildings & Improvements	27,333
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	66
Total Costs
Land	12,833
Buildings & Improvements	27,399
Total	40,232	[1]
Accumulated Depreciation	(6,621)	[2]
Net Cost Basis	33,611
100 Beaver Street
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,466
Buildings & Improvements	9,046
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	11,742
Total Costs
Land	1,466
Buildings & Improvements	20,788
Total	22,254	[1]
Accumulated Depreciation	(4,169)	[2]
Net Cost Basis	18,085
285 Bear Hill Road
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	422
Buildings & Improvements	3,538
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	5,189
Total Costs
Land	422
Buildings & Improvements	8,727
Total	9,149	[1]
Accumulated Depreciation	(340)	[2]
Net Cost Basis	8,809
111/130 Forbes Boulevard
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	3,146
Buildings & Improvements	15,725
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	2,936
Total Costs
Land	3,146
Buildings & Improvements	18,661
Total	21,807	[1]
Accumulated Depreciation	(3,940)	[2]
Net Cost Basis	17,867
20 Walkup Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	2,261
Buildings & Improvements	7,099
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	9,029
Total Costs
Land	2,261
Buildings & Improvements	16,128
Total	18,389	[1]
Accumulated Depreciation	(1,639)	[2]
Net Cost Basis	16,750
306 Belmont Street & 350 Plantation Street
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,806
Buildings & Improvements	11,696
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	1,783
Total Costs
Land	1,806
Buildings & Improvements	13,479
Total	15,285	[1]
Accumulated Depreciation	(3,594)	[2]
Net Cost Basis	11,691
30 Bearfoot Road
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,220
Buildings & Improvements	22,375
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	44
Total Costs
Land	1,220
Buildings & Improvements	22,419
Total	23,639	[1]
Accumulated Depreciation	(5,512)	[2]
Net Cost Basis	18,127
Alexandria Center for Science and Technology
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	93,813
Buildings & Improvements	210,211
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	370,840
Total Costs
Land	93,813
Buildings & Improvements	581,051
Total	674,864	[1]
Accumulated Depreciation	(53,840)	[2]
Net Cost Basis	621,024
Alexandria Technology Center - Gateway
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	98,133	[5]
Initial Costs
Land	45,425
Buildings & Improvements	121,059
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	15,378
Total Costs
Land	45,425
Buildings & Improvements	136,437
Total	181,862	[1]
Accumulated Depreciation	(35,125)	[2]
Net Cost Basis	146,737
249/259/269 East Grande Avenue
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	66,135
Initial Costs
Land	19,396
Buildings & Improvements	0
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	151,275
Total Costs
Land	19,396
Buildings & Improvements	151,275
Total	170,671	[1]
Accumulated Depreciation	(14,070)	[2]
Net Cost Basis	156,601
400 & 450 East Jamie Court
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	0
Buildings & Improvements	0
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	109,622
Total Costs
Land	0
Buildings & Improvements	109,622
Total	109,622	[1]
Accumulated Depreciation	(15,612)	[2]
Net Cost Basis	94,010
500 Forbes Boulevard
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	35,596
Buildings & Improvements	69,091
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	14,441
Total Costs
Land	35,596
Buildings & Improvements	83,532
Total	119,128	[1]
Accumulated Depreciation	(16,450)	[2]
Net Cost Basis	102,678
7000 Shoreline Court
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	31,234	[5]
Initial Costs
Land	7,038
Buildings & Improvements	39,704
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	9,070
Total Costs
Land	7,038
Buildings & Improvements	48,774
Total	55,812	[1]
Accumulated Depreciation	(11,684)	[2]
Net Cost Basis	44,128
341 & 343 Oyster Point Boulevard
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	7,038
Buildings & Improvements	0
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	31,968
Total Costs
Land	7,038
Buildings & Improvements	31,968
Total	39,006	[1]
Accumulated Depreciation	(13,517)	[2]
Net Cost Basis	25,489
839 - 863 Mitten and 866 Malcolm
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	3,211
Buildings & Improvements	8,665
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	15,307
Total Costs
Land	3,211
Buildings & Improvements	23,972
Total	27,183	[1]
Accumulated Depreciation	(8,139)	[2]
Net Cost Basis	19,044
2425 Garcia Avenue & 2450 Bayshore Parkway
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	830
Initial Costs
Land	1,512
Buildings & Improvements	21,323
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	25,150
Total Costs
Land	1,512
Buildings & Improvements	46,473
Total	47,985	[1]
Accumulated Depreciation	(16,339)	[2]
Net Cost Basis	31,646
3165 Porter Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	20,421	[4]
Initial Costs
Land	0
Buildings & Improvements	19,154
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	2,105
Total Costs
Land	0
Buildings & Improvements	21,259
Total	21,259	[1]
Accumulated Depreciation	(5,686)	[2]
Net Cost Basis	15,573
75/125 Shoreway Road
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	6,617
Buildings & Improvements	7,091
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	10,852
Total Costs
Land	6,617
Buildings & Improvements	17,943
Total	24,560	[1]
Accumulated Depreciation	(3,069)	[2]
Net Cost Basis	21,491
3350 West Bayshore Road
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	4,800
Buildings & Improvements	6,693
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	10,940
Total Costs
Land	4,800
Buildings & Improvements	17,633
Total	22,433	[1]
Accumulated Depreciation	(3,486)	[2]
Net Cost Basis	18,947
2625 & 2631 Hanover Street
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	0
Buildings & Improvements	6,628
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	10,488
Total Costs
Land	0
Buildings & Improvements	17,116
Total	17,116	[1]
Accumulated Depreciation	(7,440)	[2]
Net Cost Basis	9,676
Alexandria Center for Life Science
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	0
Buildings & Improvements	0
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	778,293
Total Costs
Land	0
Buildings & Improvements	778,293
Total	778,293	[1]
Accumulated Depreciation	(47,615)	[2]
Net Cost Basis	730,678
100 Phillips Parkway
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	9,353	[3]
Initial Costs
Land	1,840
Buildings & Improvements	2,298
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	14,897
Total Costs
Land	1,840
Buildings & Improvements	17,195
Total	19,035	[1]
Accumulated Depreciation	(7,917)	[2]
Net Cost Basis	11,118
102 Witmer Road
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,625
Buildings & Improvements	19,715
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	5,641
Total Costs
Land	1,625
Buildings & Improvements	25,356
Total	26,981	[1]
Accumulated Depreciation	(6,279)	[2]
Net Cost Basis	20,702
701 Veterans Circle
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,468
Buildings & Improvements	7,885
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	26
Total Costs
Land	1,468
Buildings & Improvements	7,911
Total	9,379	[1]
Accumulated Depreciation	(1,485)	[2]
Net Cost Basis	7,894
5100 Campus Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	256
Buildings & Improvements	2,117
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	469
Total Costs
Land	256
Buildings & Improvements	2,586
Total	2,842	[1]
Accumulated Depreciation	(1,254)	[2]
Net Cost Basis	1,588
ARE Nautilus
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	6,684
Buildings & Improvements	27,600
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	83,309
Total Costs
Land	6,684
Buildings & Improvements	110,909
Total	117,593	[1]
Accumulated Depreciation	(24,872)	[2]
Net Cost Basis	92,721
ARE Sunrise
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	19,590	[6]
Initial Costs
Land	2,954
Buildings & Improvements	15,491
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	41,518
Total Costs
Land	2,954
Buildings & Improvements	57,009
Total	59,963	[1]
Accumulated Depreciation	(29,960)	[2]
Net Cost Basis	30,003
ARE Spectrum
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	27,388
Buildings & Improvements	80,957
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	46,944
Total Costs
Land	27,388
Buildings & Improvements	127,901
Total	155,289	[1]
Accumulated Depreciation	(15,905)	[2]
Net Cost Basis	139,384
11119 North Torrey Pines Road
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	9,994
Buildings & Improvements	37,099
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	32,505
Total Costs
Land	9,994
Buildings & Improvements	69,604
Total	79,598	[1]
Accumulated Depreciation	(6,188)	[2]
Net Cost Basis	73,410
3545 Cray Court
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	39,387
Initial Costs
Land	7,056
Buildings & Improvements	53,944
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	0
Total Costs
Land	7,056
Buildings & Improvements	53,944
Total	61,000	[1]
Accumulated Depreciation	(4,864)	[2]
Net Cost Basis	56,136
5200 Illumina Way
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	38,340
Buildings & Improvements	96,606
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	73,541
Total Costs
Land	38,340
Buildings & Improvements	170,147
Total	208,487	[1]
Accumulated Depreciation	(15,176)	[2]
Net Cost Basis	193,311
9363 Towne Centre Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	8,539
Buildings & Improvements	18,850
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	3,695
Total Costs
Land	8,539
Buildings & Improvements	22,545
Total	31,084	[1]
Accumulated Depreciation	(3,431)	[2]
Net Cost Basis	27,653
10300 Campus Point Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	22,487
Buildings & Improvements	90,198
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	102,464
Total Costs
Land	22,487
Buildings & Improvements	192,662
Total	215,149	[1]
Accumulated Depreciation	(12,655)	[2]
Net Cost Basis	202,494
ARE Esplanade
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	11,452	[6]
Initial Costs
Land	9,682
Buildings & Improvements	29,991
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	45,439
Total Costs
Land	9,682
Buildings & Improvements	75,430
Total	85,112	[1]
Accumulated Depreciation	(9,459)	[2]
Net Cost Basis	75,653
ARE Towne Centre
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	34,110	[4]
Initial Costs
Land	8,539
Buildings & Improvements	18,850
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	40,293
Total Costs
Land	8,539
Buildings & Improvements	59,143
Total	67,682	[1]
Accumulated Depreciation	(31,899)	[2]
Net Cost Basis	35,783
9880 Campus Point Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	3,823
Buildings & Improvements	16,165
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	20,053
Total Costs
Land	3,823
Buildings & Improvements	36,218
Total	40,041	[1]
Accumulated Depreciation	(8,915)	[2]
Net Cost Basis	31,126
5810 & 5820 & 6138 & 6150 Nancy Ridge Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	11,435	[4]
Initial Costs
Land	5,476
Buildings & Improvements	28,682
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	1,811
Total Costs
Land	5,476
Buildings & Improvements	30,493
Total	35,969	[1]
Accumulated Depreciation	(7,743)	[2]
Net Cost Basis	28,226
ARE Portola
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	6,991
Buildings & Improvements	25,153
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	17,734
Total Costs
Land	6,991
Buildings & Improvements	42,887
Total	49,878	[1]
Accumulated Depreciation	(4,905)	[2]
Net Cost Basis	44,973
10121 & 10151 Barnes Canyon Road
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	4,608
Buildings & Improvements	5,100
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	14,257
Total Costs
Land	4,608
Buildings & Improvements	19,357
Total	23,965	[1]
Accumulated Depreciation	(188)	[2]
Net Cost Basis	23,777
7330 Carroll Road
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	4,517	[3]
Initial Costs
Land	2,650
Buildings & Improvements	19,878
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	1,253
Total Costs
Land	2,650
Buildings & Improvements	21,131
Total	23,781	[1]
Accumulated Depreciation	(2,347)	[2]
Net Cost Basis	21,434
5871 Oberlin Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,349
Buildings & Improvements	8,016
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	3,623
Total Costs
Land	1,349
Buildings & Improvements	11,639
Total	12,988	[1]
Accumulated Depreciation	(949)	[2]
Net Cost Basis	12,039
6146/6166 Nancy Ridge Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	515
Buildings & Improvements	1,566
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	2,844
Total Costs
Land	515
Buildings & Improvements	4,410
Total	4,925	[1]
Accumulated Depreciation	(2,183)	[2]
Net Cost Basis	2,742
11025 & 11045 Roselle Street
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	4,156
Buildings & Improvements	11,571
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	22,161
Total Costs
Land	4,156
Buildings & Improvements	33,732
Total	37,888	[1]
Accumulated Depreciation	(5,828)	[2]
Net Cost Basis	32,060
3985 Sorrento Valley Boulevard
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	7,333	[7]
Initial Costs
Land	4,323
Buildings & Improvements	22,846
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	3,568
Total Costs
Land	4,323
Buildings & Improvements	26,414
Total	30,737	[1]
Accumulated Depreciation	(2,651)	[2]
Net Cost Basis	28,086
Unamortized Discount	242
13112 Evening Creek Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	12,398	[6]
Initial Costs
Land	7,393
Buildings & Improvements	27,950
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	150
Total Costs
Land	7,393
Buildings & Improvements	28,100
Total	35,493	[1]
Accumulated Depreciation	(5,504)	[2]
Net Cost Basis	29,989
1201/1208 Eastlake Avenue
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	41,830	[6]
Initial Costs
Land	5,810
Buildings & Improvements	47,149
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	14,955
Total Costs
Land	5,810
Buildings & Improvements	62,104
Total	67,914	[1]
Accumulated Depreciation	(18,941)	[2]
Net Cost Basis	48,973
1616 Eastlake Avenue
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	6,940
Buildings & Improvements	0
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	82,526
Total Costs
Land	6,940
Buildings & Improvements	82,526
Total	89,466	[1]
Accumulated Depreciation	(17,874)	[2]
Net Cost Basis	71,592
1551 Eastlake Avenue
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	8,525
Buildings & Improvements	20,064
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	32,893
Total Costs
Land	8,525
Buildings & Improvements	52,957
Total	61,482	[1]
Accumulated Depreciation	(6,055)	[2]
Net Cost Basis	55,427
199 East Blaine Street
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	6,528
Buildings & Improvements	0
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	71,707
Total Costs
Land	6,528
Buildings & Improvements	71,707
Total	78,235	[1]
Accumulated Depreciation	(9,980)	[2]
Net Cost Basis	68,255
219 Terry Avenue North
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,819
Buildings & Improvements	2,302
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	18,943
Total Costs
Land	1,819
Buildings & Improvements	21,245
Total	23,064	[1]
Accumulated Depreciation	(1,705)	[2]
Net Cost Basis	21,359
1600 Fairview Avenue
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	2,212
Buildings & Improvements	6,788
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	6,009
Total Costs
Land	2,212
Buildings & Improvements	12,797
Total	15,009	[1]
Accumulated Depreciation	(2,611)	[2]
Net Cost Basis	12,398
3000/3018 Western Avenue
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,432
Buildings & Improvements	7,497
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	21,590
Total Costs
Land	1,432
Buildings & Improvements	29,087
Total	30,519	[1]
Accumulated Depreciation	(7,528)	[2]
Net Cost Basis	22,991
410 West Harrison/410 Elliott Avenue West
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	3,857
Buildings & Improvements	1,989
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	10,549
Total Costs
Land	3,857
Buildings & Improvements	12,538
Total	16,395	[1]
Accumulated Depreciation	(2,604)	[2]
Net Cost Basis	13,791
9980 Medical Center Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	76,000
Initial Costs
Land	10,052
Buildings & Improvements	99,696
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	96,305
Total Costs
Land	10,052
Buildings & Improvements	196,001
Total	206,053	[1]
Accumulated Depreciation	(40,359)	[2]
Net Cost Basis	165,694
1330 Piccard Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	2,800
Buildings & Improvements	11,533
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	28,928
Total Costs
Land	2,800
Buildings & Improvements	40,461
Total	43,261	[1]
Accumulated Depreciation	(12,517)	[2]
Net Cost Basis	30,744
1500/1550 East Gude Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,523
Buildings & Improvements	7,731
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	5,511
Total Costs
Land	1,523
Buildings & Improvements	13,242
Total	14,765	[1]
Accumulated Depreciation	(4,919)	[2]
Net Cost Basis	9,846
14920/15010 Broschart Road
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	5,804	[8]
Initial Costs
Land	4,904
Buildings & Improvements	15,846
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	3,823
Total Costs
Land	4,904
Buildings & Improvements	19,669
Total	24,573	[1]
Accumulated Depreciation	(3,152)	[2]
Net Cost Basis	21,421
Unamortized Discount	27
1405 Research Boulevard
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	899
Buildings & Improvements	21,946
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	11,515
Total Costs
Land	899
Buildings & Improvements	33,461
Total	34,360	[1]
Accumulated Depreciation	(10,165)	[2]
Net Cost Basis	24,195
5 Research Court
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,466
Buildings & Improvements	5,708
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	27,007
Total Costs
Land	1,466
Buildings & Improvements	32,715
Total	34,181	[1]
Accumulated Depreciation	(6,427)	[2]
Net Cost Basis	27,754
9920 Medical Center Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	5,791
Buildings & Improvements	8,060
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	1,071
Total Costs
Land	5,791
Buildings & Improvements	9,131
Total	14,922	[1]
Accumulated Depreciation	(2,141)	[2]
Net Cost Basis	12,781
5 Research Court
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,647
Buildings & Improvements	13,258
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	5,199
Total Costs
Land	1,647
Buildings & Improvements	18,457
Total	20,104	[1]
Accumulated Depreciation	(13,489)	[2]
Net Cost Basis	6,615
12301 Parklawn Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,476
Buildings & Improvements	7,267
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	561
Total Costs
Land	1,476
Buildings & Improvements	7,828
Total	9,304	[1]
Accumulated Depreciation	(1,912)	[2]
Net Cost Basis	7,392
Alexandria Technology Center - Gaithersburg I
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	10,183
Buildings & Improvements	59,641
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	21,652
Total Costs
Land	10,183
Buildings & Improvements	81,293
Total	91,476	[1]
Accumulated Depreciation	(22,561)	[2]
Net Cost Basis	68,915
Alexandria Technology Center - Gaithersburg II
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	4,531
Buildings & Improvements	21,594
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	31,651
Total Costs
Land	4,531
Buildings & Improvements	53,245
Total	57,776	[1]
Accumulated Depreciation	(21,028)	[2]
Net Cost Basis	36,748
16020 Industrial Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	2,924
Buildings & Improvements	19,664
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	714
Total Costs
Land	2,924
Buildings & Improvements	20,378
Total	23,302	[1]
Accumulated Depreciation	(9,349)	[2]
Net Cost Basis	13,953
401 Professional Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,129
Buildings & Improvements	6,941
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	5,745
Total Costs
Land	1,129
Buildings & Improvements	12,686
Total	13,815	[1]
Accumulated Depreciation	(4,603)	[2]
Net Cost Basis	9,212
950 Wind River Lane
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	2,400
Buildings & Improvements	10,620
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	1,050
Total Costs
Land	2,400
Buildings & Improvements	11,670
Total	14,070	[1]
Accumulated Depreciation	(1,557)	[2]
Net Cost Basis	12,513
620 Professional Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	784
Buildings & Improvements	4,705
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	7,216
Total Costs
Land	784
Buildings & Improvements	11,921
Total	12,705	[1]
Accumulated Depreciation	(1,320)	[2]
Net Cost Basis	11,385
8000/9000/10000 Virginia Manor Road
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	0
Buildings & Improvements	13,679
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	5,847
Total Costs
Land	0
Buildings & Improvements	19,526
Total	19,526	[1]
Accumulated Depreciation	(7,765)	[2]
Net Cost Basis	11,761
14225 Newbrook Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	28,297	[6]
Initial Costs
Land	4,800
Buildings & Improvements	27,639
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	6,863
Total Costs
Land	4,800
Buildings & Improvements	34,502
Total	39,302	[1]
Accumulated Depreciation	(12,542)	[2]
Net Cost Basis	26,760
Alexandria Technology Center - Alston
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,430
Buildings & Improvements	17,482
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	27,781
Total Costs
Land	1,430
Buildings & Improvements	45,263
Total	46,693	[1]
Accumulated Depreciation	(17,701)	[2]
Net Cost Basis	28,992
108/110/112/114 Alexander Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	0
Buildings & Improvements	376
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	42,050
Total Costs
Land	0
Buildings & Improvements	42,426
Total	42,426	[1]
Accumulated Depreciation	(11,837)	[2]
Net Cost Basis	30,589
Alexandria Innovation Center - Research Triangle Park
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,065
Buildings & Improvements	21,218
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	24,461
Total Costs
Land	1,065
Buildings & Improvements	45,679
Total	46,744	[1]
Accumulated Depreciation	(11,144)	[2]
Net Cost Basis	35,600
6 Davis Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	9,920
Buildings & Improvements	10,712
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	7,573
Total Costs
Land	9,920
Buildings & Improvements	18,285
Total	28,205	[1]
Accumulated Depreciation	(3,623)	[2]
Net Cost Basis	24,582
7 Triangle Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	701
Buildings & Improvements	0
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	31,643
Total Costs
Land	701
Buildings & Improvements	31,643
Total	32,344	[1]
Accumulated Depreciation	(2,914)	[2]
Net Cost Basis	29,430
407 Davis Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	1,229
Buildings & Improvements	17,733
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	0
Total Costs
Land	1,229
Buildings & Improvements	17,733
Total	18,962	[1]
Accumulated Depreciation	(683)	[2]
Net Cost Basis	18,279
2525 East NC Highway 54
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	713
Buildings & Improvements	12,827
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	894
Total Costs
Land	713
Buildings & Improvements	13,721
Total	14,434	[1]
Accumulated Depreciation	(3,685)	[2]
Net Cost Basis	10,749
601 Keystone Park Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	785
Buildings & Improvements	11,546
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	5,017
Total Costs
Land	785
Buildings & Improvements	16,563
Total	17,348	[1]
Accumulated Depreciation	(3,140)	[2]
Net Cost Basis	14,208
5 Triangle Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	161
Buildings & Improvements	3,409
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	2,857
Total Costs
Land	161
Buildings & Improvements	6,266
Total	6,427	[1]
Accumulated Depreciation	(2,074)	[2]
Net Cost Basis	4,353
6101 Quadrangle Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	951
Buildings & Improvements	3,982
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	9,462
Total Costs
Land	951
Buildings & Improvements	13,444
Total	14,395	[1]
Accumulated Depreciation	(1,221)	[2]
Net Cost Basis	13,174
555 Heritage Drive
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	2,919
Buildings & Improvements	5,311
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	11,959
Total Costs
Land	2,919
Buildings & Improvements	17,270
Total	20,189	[1]
Accumulated Depreciation	(2,461)	[2]
Net Cost Basis	17,728
661 University Avenue
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0	[9]
Initial Costs
Land	0	[9]
Buildings & Improvements	0	[9]
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	63,511	[9]
Total Costs
Land	0	[9]
Buildings & Improvements	63,511	[9]
Total	63,511	[1],[9]
Accumulated Depreciation	(12,016)	[2],[9]
Net Cost Basis	51,495	[9]
1781 W. 75th Avenue
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	2,059
Buildings & Improvements	4,244
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	8,482
Total Costs
Land	2,059
Buildings & Improvements	12,726
Total	14,785	[1]
Accumulated Depreciation	(2,235)	[2]
Net Cost Basis	12,550
7990 Enterprise Street
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	2,277
Buildings & Improvements	8,864
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	0
Total Costs
Land	2,277
Buildings & Improvements	8,864
Total	11,141	[1]
Accumulated Depreciation	(1,979)	[2]
Net Cost Basis	9,162
275 Armand Frappier
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	6,986
Buildings & Improvements	23,043
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	6,477
Total Costs
Land	6,986
Buildings & Improvements	29,520
Total	36,506	[1]
Accumulated Depreciation	(5,529)	[2]
Net Cost Basis	30,977
525 Cartier Boulevard West
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	2,926
Buildings & Improvements	18,746
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	0
Total Costs
Land	2,926
Buildings & Improvements	18,746
Total	21,672	[1]
Accumulated Depreciation	(4,604)	[2]
Net Cost Basis	17,068
510 Townsend Street [Member]
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	52,105
Buildings & Improvements	0
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	6,354
Total Costs
Land	52,105
Buildings & Improvements	6,354
Total	58,459	[1]
Accumulated Depreciation	0	[2]
Net Cost Basis	58,459
560 Eccles Avenue [Member]
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	12,093
Buildings & Improvements	0
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	5,562
Total Costs
Land	12,093
Buildings & Improvements	5,562
Total	17,655	[1]
Accumulated Depreciation	(3)	[2]
Net Cost Basis	17,652
Grand Avenue [Member]
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	37,538
Buildings & Improvements	0
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	7,518
Total Costs
Land	37,538
Buildings & Improvements	7,518
Total	45,056	[1]
Accumulated Depreciation	(21)	[2]
Net Cost Basis	45,035
China
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	0
Buildings & Improvements	0
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	85,845
Total Costs
Land	0
Buildings & Improvements	85,845
Total	85,845	[1]
Accumulated Depreciation	(3,625)	[2]
Net Cost Basis	82,220
India
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	32,433
Buildings & Improvements	0
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	139,726
Total Costs
Land	32,433
Buildings & Improvements	139,726
Total	172,159	[1]
Accumulated Depreciation	(5,746)	[2]
Net Cost Basis	166,413
Various
Consolidated Financial Statement Schedule of Rental Properties and Accumulated Depreciation
Encumbrances	0
Initial Costs
Land	64,032
Buildings & Improvements	27,141
Costs Capitalized Subsequent to Acquisition
Buildings & Improvements	266,062
Total Costs
Land	64,032
Buildings & Improvements	293,203
Total	357,235	[1]
Accumulated Depreciation	(28,564)	[2]
Net Cost Basis	328,671
7330 Carroll Road, 100 Phillips Parkway, 79/96 Thirteen Street, Alexandria Park at 128 [Member]
Total Costs
Secured notes payable	30,377
Number of real estate properties subject to secured debt	4
Alexandria at 128, 3165 Porter Drive, ARE Towne Center, 5810/5820/6138/6150 Nancy Ridge Drive [Member]
Total Costs
Secured notes payable	77,316
Number of real estate properties subject to secured debt	6
Alexandria Technology Center - Gateway, 7000 Shoreline Court [Member]
Total Costs
Secured notes payable	129,367
Number of real estate properties subject to secured debt	4
14225 Newbrook Drive, 1201 and 1208 Eastlake Avenue, 13112 Evening Creek Drive, ARE Esplanade, ARE Sunrise [Member]
Total Costs
Secured notes payable	113,567
Number of real estate properties subject to secured debt	6
Land improvements
Total Costs
Estimated useful life	20 years
Minimum | Buildings and building improvements
Total Costs
Estimated useful life	30 years
Maximum | Buildings and building improvements
Total Costs
Estimated useful life	40 years
Asset under Construction | Number 661 University Avenue [Member]
Total Costs
Area of Real Estate Property	780,540

[1] The aggregate cost of real estate for federal income tax purposes is not materially different from the cost basis under GAAP (unaudited).

[2] The depreciable life for buildings and improvements ranges from 30 to 40 years, 20 for land improvements, and the term of the respective lease for tenant improvement.

[3] Loan of $30,377 secured by four properties identified by this reference.

[4] Loan of $77,316 secured by six properties identified by this reference.

[5] Loan of $129,367 secured by four properties identified by this reference.

[6] Loan of $113,567 secured by six properties identified by this reference.

[7] The balance shown includes an unamortized premium of $242.

[8] The balance shown includes an unamortized premium of $27.

[9] Represents land and land improvements in Toronto, Canada that were classified in rental properties. This real estate was leased to a tenant and the tenant was completing the construction of a 780,540 RSF building. In December 2014, we determined that this property met the criteria to be classified as “held for sale”. In January 2015, we completed the sale