Dupont Fabros Technology 10-K 19 Feb 16 2015 Q4 Annual report Financial data

Document and Entity Information

Document and Entity Information Document - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Feb. 12, 2016	Jun. 30, 2015
Entity Information [Line Items]
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q4
Amendment Flag	false
Entity Registrant Name	DUPONT FABROS TECHNOLOGY, INC.
Entity Central Index Key	1,407,739
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Entity Common Stock, Shares Outstanding		66,649,235
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 1,909
Subsidiaries [Member]
Entity Information [Line Items]
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	Q4
Amendment Flag	false
Entity Registrant Name	DUPONT FABROS TECHNOLOGY, L.P.
Entity Central Index Key	1,418,175
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-K
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2015		Dec. 31, 2014
Income producing property:
Land	$ 94,203		$ 83,793
Buildings and improvements	2,736,936		2,623,539
Income producing property	2,831,139		2,707,332
Less: accumulated depreciation	(560,837)		(504,869)
Net income producing property	2,270,302		2,202,463
Construction in progress and land held for development	300,939	[1]	358,965
Net real estate	2,571,241		2,561,428
Cash and cash equivalents	31,230		29,598
Rents and other receivables	9,588		8,113
Deferred rent, net	128,941		142,365
Lease contracts above market value, net	6,029		8,054
Deferred costs, net	23,774		24,874
Prepaid expenses and other assets	44,689		48,295
Total assets	2,815,492		2,822,727
Liabilities:
Line of credit	0		60,000
Mortgage notes payable	114,075		113,667
Unsecured Term Loan	249,172		248,945
Unsecured notes payable	834,963		588,767
Accounts payable and accrued liabilities	32,301		26,973
Construction costs payable	22,043		32,949
Accrued interest payable	11,821		10,759
Dividend and distribution payable	43,906		39,981
Lease contracts below market value, net	4,132		7,037
Prepaid rents and other liabilities	67,477		65,174
Total liabilities	1,379,890		1,194,252
Redeemable noncontrolling interests - operating partnership	479,189		513,134
Commitments and contingencies	0		0
Stockholders’ equity:
Common stock, $.001 par value, 250,000,000 shares authorized, 66,105,650 shares issued and outstanding at December 31, 2015 and 66,061,804 shares issued and outstanding at December 31, 2014	66		66
Additional paid in capital	684,968		764,025
Retained earnings (accumulated deficit)	(79,871)		0
Total stockholders’ equity	956,413		1,115,341
Total liabilities and stockholders’ equity	2,815,492		2,822,727
Series A cumulative redeemable perpetual preferred stock [Member]
Stockholders’ equity:
Preferred stock, $.001 par value, 50,000,000 shares authorized	185,000		185,000
Series B cumulative redeemable perpetual preferred stock [Member]
Stockholders’ equity:
Preferred stock, $.001 par value, 50,000,000 shares authorized	166,250		166,250
Subsidiaries [Member]
Income producing property:
Land	94,203		83,793
Buildings and improvements	2,736,936		2,623,539
Income producing property	2,831,139		2,707,332
Less: accumulated depreciation	(560,837)		(504,869)
Net income producing property	2,270,302		2,202,463
Construction in progress and land held for development	300,939		358,965
Net real estate	2,571,241		2,561,428
Cash and cash equivalents	27,015		25,380
Rents and other receivables	9,588		8,113
Deferred rent, net	128,941		142,365
Lease contracts above market value, net	6,029		8,054
Deferred costs, net	23,774		24,874
Prepaid expenses and other assets	44,689		48,295
Total assets	2,811,277		2,818,509
Liabilities:
Line of credit	0		60,000
Mortgage notes payable	114,075		113,667
Unsecured Term Loan	249,172		248,945
Unsecured notes payable	834,963		588,767
Accounts payable and accrued liabilities	32,301		26,973
Construction costs payable	22,043		32,949
Accrued interest payable	11,821		10,759
Dividend and distribution payable	43,906		39,981
Lease contracts below market value, net	4,132		7,037
Prepaid rents and other liabilities	67,477		65,174
Total liabilities	1,379,890		1,194,252
Redeemable noncontrolling interests - operating partnership	479,189		513,134
Redeemable partnership units	479,189		513,134
Commitments and contingencies	0		0
Stockholders’ equity:
Total liabilities and stockholders’ equity	2,811,277		2,818,509
Limited partners’ capital:
General partner’s capital, common units, 662,373 issued and outstanding at December 31, 2015 and December 31, 2014	6,021		7,619
Total partners’ capital	952,198		1,111,123
Subsidiaries [Member] | Series A Preferred Units [Member]
Limited partners’ capital:
Limited partners' capital	185,000		185,000
Subsidiaries [Member] | Series B Preferred Units [Member]
Limited partners’ capital:
Limited partners' capital	166,250		166,250
Subsidiaries [Member] | Common units [Member]
Limited partners’ capital:
Limited partners' capital	594,927		752,254
Subsidiaries [Member] | Series A cumulative redeemable perpetual preferred stock [Member]
Limited partners’ capital:
Limited partners' capital	185,000		185,000
Subsidiaries [Member] | Series B cumulative redeemable perpetual preferred stock [Member]
Limited partners’ capital:
Limited partners' capital	$ 166,250		$ 166,250
[1]	(1)Properties located in Ashburn, VA (ACC7 Phases III-IV and ACC8); Piscataway, NJ (NJ1 Phase II), Elk Grove Village, IL (CH2 Phases II-III and CH3) and Santa Clara, CA (SC2). In the fourth quarter of 2015, we determined that it was more likely than not that we would sell our NJ1 data center prior to the end of its previously estimated useful life. We believe that it is unlikely that we will develop NJ1 Phase II prior to the sale.In August 2015, we acquired two parcels of land totaling 9.7 acres for a total purchase price of $8.6 million. These parcels are adjacent to our CH1 data center in Elk Grove Village, Illinois and are being held for the future development of CH3. In February 2016, we acquired two parcels of undeveloped land in Ashburn, Virginia. One parcel is a 35.4 acre site that we purchased for $15.6 million, and the other parcel is an 8.6 acre site that we purchased for $4.6 million. These parcels are being held for future development of ACC9, ACC10 and either a powered base shell or build-to-suit data center.

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2015	Dec. 31, 2014
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	50,000,000	50,000,000
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	66,105,650	66,061,804
Common stock, shares outstanding	66,105,650	66,061,804
General Partners' Capital Account, Units Issued	662,373	662,373
General partners' capital, units outstanding	662,373	662,373
Series A cumulative redeemable perpetual preferred units [Member]
Limited partners' capital, common units issued	7,400,000	7,400,000
Limited partners' capital, common units outstanding	7,400,000	7,400,000
Series B cumulative redeemable perpetual preferred units [Member]
Limited partners' capital, common units issued	6,650,000	6,650,000
Limited partners' capital, common units outstanding	6,650,000	6,650,000
Limited partners' common units [Member]
Limited partners' capital, common units issued	65,443,277	65,399,431
Limited partners' capital, common units outstanding	65,443,277	65,399,431
Series A cumulative redeemable perpetual preferred stock [Member]
Preferred stock, shares issued	7,400,000	7,400,000
Preferred stock, shares outstanding	7,400,000	7,400,000
Series B cumulative redeemable perpetual preferred stock [Member]
Preferred stock, shares issued	6,650,000	6,650,000
Preferred stock, shares outstanding	6,650,000	6,650,000

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues:
Base rent	$ 298,585	$ 285,716	$ 265,695
Recoveries from tenants	139,537	124,853	104,271
Other revenues	14,278	7,023	5,143
Total revenues	452,400	417,592	375,109
Expenses:
Property operating costs	130,051	117,339	103,522
Real estate taxes and insurance	21,335	14,195	14,380
Depreciation and amortization	104,044	96,780	93,058
General and administrative	18,064	17,181	16,261
Impairment of Long-Lived Assets to be Disposed of	122,472	0	0
Other expenses	16,859	9,222	3,650
Total expenses	412,825	254,717	230,871
Operating income	39,575	162,875	144,238
Interest income	60	116	137
Interest:
Expense incurred	(40,570)	(33,699)	(46,443)
Amortization of deferred financing costs	(3,151)	(2,980)	(3,349)
Loss on early extinguishment of debt	0	(1,701)	(40,978)
Net (loss) income	(4,086)	124,611	53,605
Noncontrolling Interest in Net Income (Loss) Operating Partnerships, Redeemable	(5,993)	18,704	5,214
Net (loss) income attributable to controlling interests	1,907	105,907	48,391
Preferred stock dividends	(27,245)	(27,245)	(27,245)
Net (loss) income attributable to common shares	$ (25,338)	$ 78,662	$ 21,146
Earnings per share – basic:
Net income attributable to common shares	$ (0.40)	$ 1.19	$ 0.32
Weighted average common shares outstanding	65,184,013	65,486,108	64,645,316
Earnings per share – diluted:
Net income attributable to common shares	$ (0.40)	$ 1.18	$ 0.32
Weighted average common shares outstanding	65,184,013	66,086,379	65,474,039
Subsidiaries [Member]
Revenues:
Base rent	$ 298,585	$ 285,716	$ 265,695
Recoveries from tenants	139,537	124,853	104,271
Other revenues	14,278	7,023	5,143
Total revenues	452,400	417,592	375,109
Expenses:
Property operating costs	130,051	117,339	103,522
Real estate taxes and insurance	21,335	14,195	14,380
Depreciation and amortization	104,044	96,780	93,058
General and administrative	18,064	17,181	16,261
Impairment of Long-Lived Assets to be Disposed of	122,472	0	0
Other expenses	16,859	9,222	3,650
Total expenses	412,825	254,717	230,871
Operating income	39,575	162,875	144,238
Interest income	60	116	137
Interest:
Expense incurred	(40,570)	(33,699)	(46,443)
Amortization of deferred financing costs	(3,151)	(2,980)	(3,349)
Loss on early extinguishment of debt	0	(1,701)	(40,978)
Net (loss) income	(4,086)	124,611	53,605
Preferred stock dividends	(27,245)	(27,245)	(27,245)
Net income attributable to common units	$ (31,331)	$ 97,366	$ 26,360
Earnings per unit – basic:
Net income attributable to common units	$ (0.40)	$ 1.19	$ 0.32
Weighted average common units outstanding	80,599,199	81,053,127	80,580,556
Earnings per unit – diluted:
Net income attributable to common units	$ (0.40)	$ 1.18	$ 0.32
Weighted average common units outstanding	80,599,199	81,653,398	81,409,279

Consolidated Statements of Stoc

Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	PreferredStock/Units [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]
Balance at Dec. 31, 2012	$ 1,266,432	$ 351,250	$ 63	$ 915,119	$ 0
Balance, shares at Dec. 31, 2012	63,340,929
Net income attributable to controlling interests	$ 48,391				48,391
Dividends declared on common stock	(61,560)			(40,414)	(21,146)
Dividends earned on preferred stock	(27,245)				(27,245)
Redemption of operating partnership units	$ 75,600		3	75,597
Redemption of operating partnership units, shares	3,115,269
Common stock repurchases	$ (37,792)		(1)	(37,791)
Common stock repurchase, shares	(1,632,673)
Issuance of stock awards	$ 319		0	319
Issuance of stock awards, shares	216,209
Stock Issued During Period, Value, Stock Options Exercised	$ 1,711		0	1,711
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	250,472
Retirement and forfeiture of stock awards	$ (1,172)		0	(1,172)
Retirement and forfeiture of stock awards, shares	(84,932)
Amortization of deferred compensation costs	$ 6,381			6,381
Adjustments to redeemable noncontrolling interests – operating partnership	(18,791)			(18,791)
Balance at Dec. 31, 2013	$ 1,252,274	351,250	65	900,959	0
Balance, shares at Dec. 31, 2013	65,205,274
Net income attributable to controlling interests	$ 105,907				105,907
Dividends declared on common stock	(96,866)			(18,204)	(78,662)
Dividends earned on preferred stock	(27,245)				(27,245)
Redemption of operating partnership units	$ 6,100		0	6,100
Redemption of operating partnership units, shares	234,300
Common stock repurchase, shares	0
Issuance of stock awards	$ 360		0	360
Issuance of stock awards, shares	163,187
Stock Issued During Period, Value, Stock Options Exercised	$ 5,556		1	5,555
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	507,056
Retirement and forfeiture of stock awards	$ (1,193)		0	(1,193)
Retirement and forfeiture of stock awards, shares	(48,013)
Amortization of deferred compensation costs	$ 6,565			6,565
Adjustments to redeemable noncontrolling interests – operating partnership	(136,117)			(136,117)
Balance at Dec. 31, 2014	$ 1,115,341	351,250	66	764,025	0
Balance, shares at Dec. 31, 2014	66,061,804
Net income attributable to controlling interests	$ 1,907				1,907
Dividends declared on common stock	(113,450)			(58,917)	(54,533)
Dividends earned on preferred stock	(27,245)				(27,245)
Redemption of operating partnership units	$ 9,544		0	9,544
Redemption of operating partnership units, shares	363,674
Common stock repurchases	$ (31,912)		(1)	(31,911)
Common stock repurchase, shares	(1,002,610)
Issuance of stock awards	$ 2,239		1	2,238
Issuance of stock awards, shares	565,162
Stock Issued During Period, Value, Stock Options Exercised	$ 7,930		0	7,930
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	362,642
Retirement and forfeiture of stock awards	$ (7,682)		0	(7,682)
Retirement and forfeiture of stock awards, shares	(245,022)
Amortization of deferred compensation costs	$ 7,846			7,846
Adjustments to redeemable noncontrolling interests – operating partnership	(8,105)			(8,105)
Balance at Dec. 31, 2015	$ 956,413	$ 351,250	$ 66	$ 684,968	$ (79,871)
Balance, shares at Dec. 31, 2015	66,105,650

Consolidated Statement of Partn

Consolidated Statement of Partners' Capital - USD ($) $ in Thousands	Total	Subsidiaries [Member]	Subsidiaries [Member]Limited Partners' Capital - Preferred [Member]	Subsidiaries [Member]Limited Partners' Capital - Common [Member]	Subsidiaries [Member]General Partner's Capital [Member]
Balance at Dec. 31, 2012		$ 1,262,136	$ 351,250	$ 901,361	$ 9,525
Balance, units at Dec. 31, 2012				62,678,556	662,373
Net (loss) income	$ 53,605	53,605		$ 53,060	$ 545
Common unit distributions		(76,610)		(75,981)	(629)
Preferred unit distributions		$ (27,245)		$ (26,968)	(277)
Issuance of OP units to DFT when redeemable partnership units redeemed, units	3,115,269	3,115,269		3,115,269
Issurance of OP units to DFT when redeemable partnership units redeemed	$ 75,600	$ 75,600		$ 75,600
Retirement of OP units for common stock repurchase, units				(1,632,673)
Retirement of OP units for common stock repurchases		(37,792)		$ (37,792)
Issuance of OP units for stock awards, units				216,209
Issuance of OP units for stock awards		319		$ 319
Issuance of OP units due to option exercises, units				250,472
Issuance of OP units due to option exercises		1,711		$ 1,711
Retirement and forfeiture of OP units, units				(84,932)
Retirement and forfeiture of OP units		(1,172)		$ (1,172)
Amortization of deferred compensation costs	6,381	6,381		6,381
Adjustments to redeemable partnership units		(8,878)		(8,824)	(54)
Balance at Dec. 31, 2013		1,248,055	351,250	$ 887,695	$ 9,110
Balance, units at Dec. 31, 2013				64,542,901	662,373
Net (loss) income	$ 124,611	124,611		$ 123,362	$ 1,249
Common unit distributions		(119,697)		(118,723)	(974)
Preferred unit distributions		$ (27,245)		$ (26,972)	(273)
Issuance of OP units to DFT when redeemable partnership units redeemed, units	234,300	234,300		234,300
Issurance of OP units to DFT when redeemable partnership units redeemed	$ 6,100	$ 6,100		$ 6,100
Issuance of OP units for stock awards, units				163,187
Issuance of OP units for stock awards		360		$ 360
Issuance of OP units due to option exercises, units				507,056
Issuance of OP units due to option exercises		5,556		$ 5,556
Retirement and forfeiture of OP units, units				(48,013)
Retirement and forfeiture of OP units		(1,193)		$ (1,193)
Amortization of deferred compensation costs	6,565	6,565		6,565
Adjustments to redeemable partnership units		(131,989)		(130,496)	(1,493)
Balance at Dec. 31, 2014		1,111,123	351,250	$ 752,254	$ 7,619
Balance, units at Dec. 31, 2014				65,399,431	662,373
Net (loss) income	$ (4,086)	(4,086)		$ (4,045)	$ (41)
Common unit distributions		(139,963)		(138,817)	(1,146)
Preferred unit distributions		$ (27,245)		$ (26,972)	(273)
Issuance of OP units to DFT when redeemable partnership units redeemed, units	363,674	363,674		363,674
Issurance of OP units to DFT when redeemable partnership units redeemed	$ 9,544	$ 9,544		$ 9,544
Retirement of OP units for common stock repurchase, units				(1,002,610)
Retirement of OP units for common stock repurchases		(31,912)		$ (31,912)
Issuance of OP units for stock awards, units				565,162
Issuance of OP units for stock awards		2,239		$ 2,239
Issuance of OP units due to option exercises, units				362,642
Issuance of OP units due to option exercises		7,930		$ 7,930
Retirement and forfeiture of OP units, units				(245,022)
Retirement and forfeiture of OP units		(7,682)		$ (7,682)
Amortization of deferred compensation costs	$ 7,846	7,846		7,846
Adjustments to redeemable partnership units		24,404		24,542	(138)
Balance at Dec. 31, 2015		$ 952,198	$ 351,250	$ 594,927	$ 6,021
Balance, units at Dec. 31, 2015				65,443,277	662,373

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flow from operating activities
Net (loss) income	$ (4,086)	$ 124,611	$ 53,605
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation, Depletion and Amortization	104,044	96,780	93,058
Impairment of Long-Lived Assets to be Disposed of	122,472	0	0
Write off of Deferred Debt Issuance Cost	0	1,701	40,978
Straight line rent	13,424	7,673	(6,920)
Amortization of deferred financing costs	(3,151)	(2,980)	(3,349)
Amortization of lease contracts above and below market value	(880)	(2,393)	(2,391)
Compensation paid with Company common shares	9,303	6,191	6,088
Changes in operating assets and liabilities
Rents and other receivables	(1,475)	4,561	(5,900)
Deferred costs	(4,233)	(2,552)	(2,082)
Prepaid expenses and other assets	4,901	(5,637)	(14,760)
Accounts payable and accrued liabilities	5,053	1,395	1,520
Accrued interest payable	1,062	776	7,382
Prepaid rents and other liabilities	2,285	8,427	19,834
Net cash provided by operating activities	255,021	244,513	193,761
Cash flow from investing activities
Investments in real estate – development	(217,339)	(265,374)	(129,332)
Payments to Acquire Land	(8,600)	0	(14,186)
Interest capitalized for real estate under development	(11,564)	(9,644)	(3,774)
Improvements to real estate	(3,459)	(1,916)	(5,757)
Additions to non-real estate property	(753)	(316)	(71)
Net cash used in investing activities	(241,715)	(277,250)	(153,120)
Line of credit:
Proceeds	120,000	60,000	102,000
Repayments	(180,000)	0	(120,000)
Mortgage notes payable:
Proceeds	0	0	115,000
Lump sum payoffs	0	0	(138,300)
Repayments	0	0	(1,300)
Unsecured Term Loan:
Proceeds	0	96,000	154,000
Unsecured notes payable:
Proceeds	248,012	0	600,000
Repayments	0	0	(550,000)
Payments of financing costs	(4,740)	(3,829)	(18,200)
Payments for early extinguishment of debt	0	0	(32,544)
Equity compensation (payments) proceeds	249	4,363	1,711
Common stock repurchases	(31,912)	0	(37,792)
Dividends and distributions:
Common shares	(110,126)	(85,422)	(57,927)
Preferred shares	(27,245)	(27,245)	(27,245)
Redeemable noncontrolling interests – operating partnership	(25,912)	(20,265)	(14,889)
Net cash provided by financing activities	(11,674)	23,602	(25,486)
Net increase (decrease) in cash and cash equivalents	1,632	(9,135)	15,155
Cash and cash equivalents, beginning	29,598	38,733	23,578
Cash and cash equivalents, ending	31,230	29,598	38,733
Supplemental information:
Cash paid for interest	51,073	42,567	42,835
Deferred financing costs capitalized for real estate under development	737	601	226
Construction costs payable capitalized for real estate under development	22,043	32,949	45,444
Redemption of operating partnership units	9,544	6,100	75,600
Adjustments to redeemable noncontrolling interests – operating partnership	8,105	136,117	18,791
Subsidiaries [Member]
Cash flow from operating activities
Net (loss) income	(4,086)	124,611	53,605
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation, Depletion and Amortization	104,044	96,780	93,058
Impairment of Long-Lived Assets to be Disposed of	122,472	0	0
Write off of Deferred Debt Issuance Cost	0	1,701	40,978
Straight line rent	13,424	7,673	(6,920)
Amortization of deferred financing costs	(3,151)	(2,980)	(3,349)
Amortization of lease contracts above and below market value	(880)	(2,393)	(2,391)
Compensation paid with Company common shares	9,303	6,191	6,088
Changes in operating assets and liabilities
Rents and other receivables	(1,475)	4,561	(5,900)
Deferred costs	(4,233)	(2,552)	(2,082)
Prepaid expenses and other assets	4,901	(5,637)	(14,760)
Accounts payable and accrued liabilities	5,053	1,396	1,520
Accrued interest payable	1,062	776	7,382
Prepaid rents and other liabilities	2,288	8,427	19,834
Net cash provided by operating activities	255,024	244,514	193,761
Cash flow from investing activities
Investments in real estate – development	(217,339)	(265,374)	(129,332)
Payments to Acquire Land	(8,600)	0	(14,186)
Interest capitalized for real estate under development	(11,564)	(9,644)	(3,774)
Improvements to real estate	(3,459)	(1,916)	(5,757)
Additions to non-real estate property	(753)	(316)	(71)
Net cash used in investing activities	(241,715)	(277,250)	(153,120)
Line of credit:
Proceeds	120,000	60,000	102,000
Repayments	(180,000)	0	(120,000)
Mortgage notes payable:
Proceeds	0	0	115,000
Lump sum payoffs	0	0	(138,300)
Repayments	0	0	(1,300)
Unsecured Term Loan:
Proceeds	0	96,000	154,000
Unsecured notes payable:
Proceeds	248,012	0	600,000
Repayments	0	0	(550,000)
Payments of financing costs	(4,740)	(3,829)	(18,123)
Payments for early extinguishment of debt	0	0	(32,544)
Equity compensation (payments) proceeds	249	4,363	1,711
Common stock repurchases	(31,912)	0	(37,792)
Distributions	(163,283)	(132,932)	(100,061)
Dividends and distributions:
Net cash provided by financing activities	(11,674)	23,602	(25,409)
Net increase (decrease) in cash and cash equivalents	1,635	(9,134)	15,232
Cash and cash equivalents, beginning	25,380	34,514	19,282
Cash and cash equivalents, ending	27,015	25,380	34,514
Supplemental information:
Cash paid for interest	51,073	42,567	42,835
Deferred financing costs capitalized for real estate under development	737	601	226
Construction costs payable capitalized for real estate under development	22,043	32,949	45,444
Redemption of operating partnership units	9,544	6,100	75,600
Adjustments to redeemable noncontrolling interests – operating partnership	$ (24,404)	$ 131,989	$ 8,878

1. Description of Business

1. Description of Business	12 Months Ended
	Dec. 31, 2015
Description of Business [Abstract]
Nature of Operations [Text Block]	Description of Business DuPont Fabros Technology, Inc. (“DFT”), through its controlling interest in DuPont Fabros Technology, L.P. (the “Operating Partnership” or “OP” and collectively with DFT and their operating subsidiaries, the “Company”), is a fully integrated, self-administered and self-managed company that owns, acquires, develops and operates wholesale data centers. DFT is a real estate investment trust, or REIT, for federal income tax purposes and is the sole general partner of the Operating Partnership, and as of December 31, 2015 , owned 81.4% of the common economic interest in the Operating Partnership, of which 1.0% is held as general partnership units. Unless otherwise indicated or unless the context requires otherwise, all references in this report to “we,” “us,” “our,” “our Company” or “the Company” refer to DFT and the Operating Partnership, collectively. As of December 31, 2015 , we held a fee simple interest in the following properties: • 12 operating data centers – ACC2, ACC3, ACC4, ACC5, ACC6, ACC7 Phases I-II, VA3, VA4, CH1, CH2 Phase I, NJ1 Phase I and SC1; • three data centers currently under development – ACC7 Phase III, CH2 Phase II and CH2 Phase III; • data center projects available for future development – ACC7 Phase IV and NJ1 Phase II; and • land that may be used to develop additional data centers – ACC8, CH3, and SC2. In January 2016, we announced that we are marketing our NJ1 data center facility for sale. We believe that it is unlikely that we will develop NJ1 Phase II prior to the sale. In February 2016, we purchased two parcels of land in Ashburn, VA totaling 44 acres. One of these parcels is inside our Ashburn Corporate Campus and one is adjacent to it. This land is being held for the future development of two new data center facilities to be known as ACC9 and ACC10, and a powered base shell or build-to-suit development.

2. Significant Accounting Polic

2. Significant Accounting Policies	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Significant Accounting Policies [Text Block]	Significant Accounting Policies Basis of Presentation This report combines the annual reports on Form 10-K for the year ended December 31, 2015 of DuPont Fabros Technology, Inc. and DuPont Fabros Technology, L.P. References to “DFT” mean DuPont Fabros Technology, Inc. and its controlled subsidiaries; and references to the “Operating Partnership” or “OP” mean DuPont Fabros Technology, L.P. and its controlled subsidiaries. We believe combining the annual reports on Form 10-K of DFT and the Operating Partnership into this single report provides the following benefits: • enhances investors’ understanding of DFT and the Operating Partnership by enabling investors to view the business as a whole in the same manner as management views and operates the business; • eliminates duplicative disclosure and provides a more streamlined and readable presentation since a substantial portion of the disclosure in this report applies to both DFT and the Operating Partnership; and • creates time and cost efficiencies through the preparation of one combined report instead of two separate reports. We operate DFT and the Operating Partnership as one business. The management of DFT consists of the same employees as the management of the Operating Partnership. We believe it is important for investors to understand the few differences between DFT and the Operating Partnership in the context of how DFT and the Operating Partnership operate as a consolidated company. DFT is a REIT, whose only material asset is its ownership of OP units of the Operating Partnership. As a result, DFT does not conduct business itself, other than acting as the sole general partner of the Operating Partnership, issuing public equity from time to time and guaranteeing unsecured debt of the Operating Partnership. DFT has not issued any indebtedness, but has guaranteed all of the unsecured debt of the Operating Partnership. The Operating Partnership, through its wholly-owned subsidiaries, holds all the real estate assets of the Company. Except for net proceeds from public equity issuances by DFT, which are contributed to the Operating Partnership in exchange for OP units or preferred units, the Operating Partnership generates all remaining capital required by our business. These sources include the Operating Partnership’s operations, its direct or indirect incurrence of indebtedness, and the issuance of partnership units. As general partner with control of the Operating Partnership, DFT consolidates the Operating Partnership for financial reporting purposes. The presentation of stockholders’ equity and partners’ capital are the main areas of difference between the consolidated financial statements of DFT and those of the Operating Partnership. The Operating Partnership’s capital includes preferred units and general and limited common units that are owned by DFT and the other partners. DFT’s stockholders’ equity includes preferred stock, common stock, additional paid in capital and retained earnings. The common limited partnership interests held by the limited partners (other than DFT) in the Operating Partnership are presented as “redeemable partnership units” in the Operating Partnership’s consolidated financial statements and as “redeemable noncontrolling interests-operating partnership” in DFT’s consolidated financial statements. The only difference between the assets and liabilities of DFT and the Operating Partnership as of December 31, 2015 is a $4.2 million bank account held by DFT that is not part of the Operating Partnership. Net income is the same for DFT and the Operating Partnership. The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles, or GAAP. All significant intercompany accounts and transactions have been eliminated in the consolidated financial statements. We have one reportable segment consisting of investments in data centers located in the United States. All of our properties generate similar types of revenues and expenses related to customer rent and reimbursements and operating expenses. The delivery of our products is consistent across all properties and although services are provided to a range of customers, the types of services provided to them are limited to a few core principles. As such, the properties in our portfolio have similar economic characteristics and the nature of the products and services provided to our customers and the method to distribute such services are consistent throughout the portfolio. Use of Estimates The preparation of financial statements in conformity with GAAP requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosures of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates. Property All capital improvements for the income-producing properties that extend their useful life are capitalized to individual building components, including interest and real estate taxes incurred during the period of development, and depreciated over their estimated useful lives. Interest is capitalized during the period of development based upon applying the property’s specific borrowing rate to the actual development costs expended up to specific borrowings, if any, and then applying our weighted-average borrowing rate to any residual development costs expended during the construction period. Interest is capitalized until the property has reached substantial completion and is ready for its intended use. Interest costs capitalized totaled $12.3 million , $10.2 million and $4.0 million for the years ended December 31, 2015 , 2014 and 2013 , respectively. We cease interest capitalization when a development is temporarily suspended or placed in service. We capitalize pre-development costs, including internal costs, incurred in pursuit of new development opportunities for which we believe future development is probable. Future development is dependent upon various factors, including zoning and regulatory approval, rental market conditions, construction costs and availability of capital. Pre-development costs incurred for which future development is not yet considered probable are expensed as incurred. In addition, if the status of such a pre-development opportunity changes, making future development no longer probable, any capitalized pre-development costs are written-off with a charge to expense. Furthermore, the revenue from incidental operations received from the current improvements in excess of any incremental costs are recorded as a reduction of total capitalized costs of the development project and not as a part of net income. The capitalization of costs during the development of assets (including interest and related loan fees, property taxes and other direct and indirect costs) begins when development efforts commence and ends when the asset, or a portion of the asset, is substantially complete and ready for its intended use. For the years ended December 31, 2015 , 2014 and 2013 , we capitalized $7.5 million , $4.5 million and $3.3 million , respectively, of internal development and leasing costs on all of our data centers. The fair value of in-place leases consists of the following components, as applicable: (1) the estimated cost to replace the leases, including foregone rents during the period of finding a new customer, foregone recovery of customer pass-through, customer improvements, and other direct costs associated with obtaining a new customer (referred to as tenant origination costs); (2) the estimated leasing commissions associated with obtaining a new customer (referred to as leasing commissions); and (3) the above/below market cash flow of the leases, determined by comparing the projected cash flows of the leases in place to projected cash flows of comparable market-rate leases (referred to as lease intangibles). Tenant origination costs are included in buildings and improvements in our accompanying consolidated balance sheets and are amortized as depreciation expense on a straight-line basis over the average remaining life of the underlying leases. Leasing commissions are classified as deferred costs and are amortized as amortization expense on a straight-line basis over the remaining life of the underlying leases. Lease intangible assets and liabilities are classified as lease contracts above and below market value, respectively, and amortized on a straight-line basis as decreases and increases, respectively, to rental revenue over the remaining life of the underlying leases. Should a customer terminate its lease early, the unamortized portions of leasing commissions and lease intangibles associated with that lease are written off to amortization expense or rental revenue, respectively, as further described below. Depreciation on buildings is generally provided on a straight-line basis over 40 years from the date the buildings were placed in service. Building components are depreciated over the life of the respective improvement ranging from 10 to 40 years from the date the components were placed in service. Personal property is depreciated over three years to seven years . Depreciation expense was $98.8 million , $92.3 million and $88.6 million for the years ended December 31, 2015 , 2014 and 2013 , respectively. Included in these amounts is amortization expense related to tenant origination costs, which was $2.0 million for the year ended December 31, 2015 , and $3.1 million for each of the years ended December 31, 2014 and 2013 . Repairs and maintenance costs are expensed as incurred. We review each of our properties for indicators of impairment. Examples of such indicators may include a significant decrease in the market price of the property, a significant adverse change in the extent or manner in which the property is being used in its physical condition, a significant adverse change in legal factors or in the business climate that could affect the value of a property, including an adverse action or assessment by a regulator, an accumulation of costs significantly in excess of the amount originally expected for the development of a property, a history of operating or cash flow losses of the property or a current expectation that, more likely than not, a property will be sold or otherwise disposed of significantly before the end of its previously estimated useful life. When such impairment indicators exist, we review an estimate of the future undiscounted net cash flows expected to result from the real estate investment’s use and eventual disposition and compare that estimate to the carrying value of the property. We assess the recoverability of the carrying value of our assets on a property-by-property basis. We consider factors such as future operating income, trends and prospects, as well as the effects of leasing demand, competition, potential sales proceeds and other factors. If our undiscounted cash flow evaluation indicates that we are unable to recover the carrying value of a real estate investment, an impairment loss is recorded to the extent that the carrying value exceeds the estimated fair value of the property. In the fourth quarter of 2015, we identified our NJ1 data center as an asset that fell outside of our strategic focus on wholesale data center development and operations in our targeted markets, and it became evident that we would, more likely than not, sell NJ1 prior to its previously estimated useful life. In connection with that determination, we evaluated the recoverability of the carrying value for NJ1 and determined that its carrying value was no longer recoverable due to reducing its expected holding period. As a result, for the year ended December 31, 2015, we reduced the carrying value of NJ1 to its estimated fair value by recording an impairment charge of $122.5 million . Estimated fair value was determined using a third party appraisal for NJ1 in conjunction with the guidance in ASC 820, which involved the use of Level 3 inputs. The appraisal was based on the income capitalization approach which derives value using the property's potential income and an average market capitalization rate for comparable sales in the market. There were no impairment losses for the years ended December 31, 2014 and 2013. We classify a data center property as held-for-sale when it meets the necessary criteria, which include when we commit to and actively embark on a plan to sell the asset, the sale is expected to be completed within one year under terms usual and customary for such sales, and actions required to complete the plan indicate that it is unlikely that significant changes to the plan will be made or that the plan will be withdrawn. Data center properties held-for-sale are carried at the lower of cost or fair value less costs to sell. Because we have never sold a data center facility since becoming a public company in 2007 and therefore have no history of selling data center assets, we are not reasonably assured that the sale of NJ1 will occur within one year. Accordingly, as of December 31, 2015 , we did not classify our NJ1 data center, nor any of our other data centers, as held-for-sale. Cash and Cash Equivalents We consider all demand deposits and money market accounts purchased with a maturity date of three months or less, at the date of purchase, to be cash equivalents. Our account balances at one or more institutions exceed the Federal Deposit Insurance Corporation (“FDIC”) insurance coverage and, as a result, there is a concentration of credit risk related to amounts on deposit in excess of FDIC insurance coverage. We have not experienced any losses and believe that the risk is not significant. Deferred Costs Deferred costs, net in our accompanying consolidated balance sheets include both financing and leasing costs. Deferred financing costs represent fees and other costs incurred in obtaining our unsecured line of credit. As of December 31, 2015 , we have early-adopted Accounting Standards Update ("ASU") 2015-03, Interest—Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs , which changed the presentation of deferred financing costs in our accompanying consolidated balance sheets. The new guidance requires that deferred financing costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the debt liability rather than as an asset. However, the FASB subsequently issued ASU 2015-15, Interest—Imputation of Interest (Subtopic 835-30): Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of-Credit Arrangements , which allows an entity to continue to present line of credit issuance costs as an asset, regardless of whether there are any outstanding borrowings on the line of credit. Accordingly, for each of our recognized debt liabilities other than our unsecured revolving credit facility ("Unsecured Credit Facility"), we have reduced these balances by their respective deferred financing cost balances, net of accumulated amortization, and have applied this change retrospectively to all periods presented. Balances of financing costs for our Unsecured Credit Facility, net of accumulated amortization, which are presented within deferred costs, net in our accompanying consolidated balance sheets at December 31, 2015 and 2014 , are as follows (in thousands): December 31, Financing costs presented within deferred costs, net 2015 2014 Financing costs $ 8,198 $ 7,448 Accumulated amortization (4,969 ) (3,779 ) Financing costs, net $ 3,229 $ 3,669 Balances of financing costs for our other recognized debt liabilities, net of accumulated amortization, which are presented as a reduction of each of the respective recognized debt liabilities in our accompanying consolidated balance sheets at December 31, 2015 and 2014 , are as follows (in thousands): December 31, Financing costs presented as a reduction of debt liability balances 2015 2014 Financing costs $ 20,531 $ 16,662 Accumulated amortization (5,618 ) (3,041 ) Financing costs, net $ 14,913 $ 13,621 Financing costs are amortized using the effective-interest rate method or a method that approximates the effective-interest method, over the term of the loan and are included in amortization of deferred financing costs in our consolidated statements of operations. In May 2014, we amended our Unsecured Credit Facility, which, due to the change in composition of lenders comprising the Unsecured Credit Facility's bank group, resulted in the partial write-off of unamortized deferred financing costs totaling $0.3 million . In July 2014, we amended our unsecured term loan agreement ("Unsecured Term Loan"), which, due to the change in composition of lenders comprising the Unsecured Term Loan's bank group, resulted in a loss on early extinguishment of debt of $1.4 million , which included a partial write-off of unamortized deferred financing costs of $0.7 million . In March 2013, we paid off the $138.3 million balance of a term loan which resulted in a write-off of $1.7 million of unamortized deferred financing costs. In September and October 2013, we paid off our senior unsecured notes due 2017 (the "Unsecured Notes due 2017"), which resulted in a write off of $6.7 million of unamortized deferred financing costs. Leasing costs, which include external fees and costs incurred in the successful negotiations of leases, internal costs expended in the successful negotiations of leases or the estimated leasing commissions resulting from the allocation of the purchase price of ACC2, VA3, VA4 and ACC4, are deferred and amortized over the terms of the related leases on a straight-line basis. If an applicable lease terminates prior to the expiration of its initial term, the carrying amount of the costs are written off to amortization expense. In June 2015, we wrote off $0.7 million of unamortized leasing costs to amortization expense related to a former customer in bankruptcy whose leases with us were rejected effective July 1, 2015 pursuant to an order made by the bankruptcy court, described below. Leasing costs incurred for the years ended December 31, 2015 , 2014 and 2013 are as follows (in millions): Year ended December 31, 2015 2014 2013 Costs incurred for new leases $ 2.1 $ 2.0 $ 0.9 Costs incurred for renewals 1.2 0.2 1.2 Costs incurred for re-leases 0.9 2.0 — Total leasing costs incurred $ 4.2 $ 4.2 $ 2.1 Amortization of deferred leasing costs totaled $4.9 million , $4.1 million and $4.1 million for the years ended December 31, 2015 , 2014 and 2013 , respectively. Balances, net of accumulated amortization, at December 31, 2015 and 2014 are as follows (in thousands): December 31, 2015 2014 Leasing costs $ 50,503 $ 52,358 Accumulated amortization (29,958 ) (31,153 ) Leasing costs, net $ 20,545 $ 21,205 Inventory We maintain fuel inventory for our generators, which is recorded at the lower of cost (on a first-in, first-out basis) or market. As of December 31, 2015 and 2014 , the fuel inventory was $4.5 million and $4.3 million , respectively, and is included in prepaid expenses and other assets in the accompanying consolidated balance sheets. Prepaid Rents Prepaid rents, typically prepayment of the following month’s rent, consist of payments received from customers prior to the time the payments are earned and are recognized as revenue in subsequent periods when earned. Rental Income We, as a lessor, have retained substantially all the risks and benefits of ownership and account for our leases as operating leases. For lease agreements that provide for scheduled fixed and determinable rent increases, rental income is recognized on a straight-line basis over the non-cancellable term of the leases, which commences when control of the space and critical power have been provided to the customer. If the lease contains an early termination clause with a penalty payment, we determine the lease termination date by evaluating whether the penalty reasonably assures that the lease will not be terminated early. Straight-line rents receivable are included in deferred rent, net in the accompanying consolidated balance sheets. Lease inducements, which include free rent or cash payments to customers, are amortized as a reduction of rental income over the non-cancellable lease term. Lease inducements are included in prepaid expenses and other assets in the accompanying consolidated balance sheets. Lease intangible assets and liabilities that have resulted from above-market and below-market leases that were acquired are amortized on a straight-line basis as decreases and increases, respectively, to rental revenue over the remaining non-cancellable term of the underlying leases. If a lease terminates prior to the expiration of its initial term, the unamortized portion of straight-line rents receivable, lease inducements and lease intangibles associated with that lease will be written off to rental revenue. In June 2015, we wrote-off as a reduction of base rent $0.4 million of unreserved straight-line rents receivable, $0.1 million of unamortized lease inducements and $1.0 million of unamortized lease intangibles related to a former customer in bankruptcy whose leases with us were rejected effective July 1, 2015 pursuant to an order made by the bankruptcy court. Balances, net of accumulated amortization, at December 31, 2015 and 2014 are as follows (in thousands): December 31, 2015 2014 Lease contracts above market value $ 20,500 $ 23,100 Accumulated amortization (14,471 ) (15,046 ) Lease contracts above market value, net $ 6,029 $ 8,054 Lease contracts below market value $ 24,175 $ 39,375 Accumulated amortization (20,043 ) (32,338 ) Lease contracts below market value, net $ 4,132 $ 7,037 Our policy is to record a reserve for losses on accounts receivable equal to the estimated uncollectible accounts. The estimate is based on our historical experience and a review of the current status of our receivables. As of December 31, 2015 and 2014 , we had one potentially uncollectible account that consisted of a note receivable from a customer in bankruptcy. The note balance as of December 31, 2015 and 2014 was $6.5 million and $6.6 million , respectively, which is recorded within rents and other receivables, net in our accompanying consolidated balance sheets. The note has been non-accrual over its term, and we applied interest received to the note principal balance totaling $1.2 million . As of December 31, 2015 and 2014 , respectively, we have established a reserve of $5.1 million and $4.9 million , including interest applied to principal. The note receivable, net of reserves and interest applied to the principal, was $1.4 million and $1.7 million as of December 31, 2015 and 2014 , respectively. In October 2015, a sale of our bankrupt customer's east coast business was consummated, and we continue to be reasonably assured that we will be able to collect the balance of the note receivable, net of reserve, as a claim in the bankruptcy. We also establish an appropriate allowance for doubtful accounts for receivables arising from the straight-lining of rents. These receivables arise from revenue recognized in excess of amounts currently due under the lease and are recorded as deferred rent, net in the accompanying consolidated balance sheets. As of December 31, 2014 , we had reserves against deferred rent relating to the leases with the now former customer in bankruptcy of $3.6 million . Due to the rejection of leases by this customer, we wrote off the reserved straight-line rent receivable for this customer in the second quarter of 2015. As of December 31, 2015 , we had reserves against deferred rent of $0.1 million . Customer leases generally contain provisions under which the customers reimburse us for a portion of operating expenses and real estate taxes incurred by the property. Recoveries from tenants are included in revenue in the accompanying consolidated statements of operations in the period the applicable expenditures are incurred. Most of our leases also provide us with a property management fee based on a percentage of base rent collected and property-level operating expenses, other than charges for power used by customers to run their servers and cool their space. Property management fees are included in base rent in the accompanying consolidated statements of operations in the applicable period in which they are earned. Other Revenue Other revenue primarily consists of services provided to customers on a non-recurring basis. This includes projects such as the purchase and installation of circuits, racks, breakers and other customer requested items. Revenue is recognized on a completed contract basis when the project is finished and ready for the customer's use. This method is consistently applied for all periods presented. Costs of providing these services are included in other expenses in the accompanying consolidated statements of operations. Income Taxes DFT elected to be taxed as a REIT under the Internal Revenue Code of 1986, as amended (the “Code”), commencing with the taxable year ended December 31, 2007. In general, a REIT that meets certain organizational and operational requirements and distributes at least 90 percent of its REIT taxable income to its shareholders in a year will not be subject to income tax to the extent of the income it distributes. We currently qualify and intend to continue to qualify as a REIT under the Code. As a result, no provision for federal income taxes on income from continuing operations is required, except for taxes on certain property sales and on income, if any, of DF Technical Services, LLC, our taxable REIT subsidiary (“TRS”). If we fail to qualify as a REIT in any taxable year, we will be subject to federal income tax (including any applicable alternative minimum tax) on our income at regular corporate tax rates for the year in which we do not qualify and the succeeding four years. Although we expect to qualify for taxation as a REIT, we may be subject to state and local income and franchise taxes and to federal income and excise taxes on any undistributed income. As of December 31, 2015 and 2014 , we did not have any unrecognized tax benefits. We do not believe that there will be any material changes in our unrecognized tax positions over the next 12 months. We are subject to examination by the respective taxing authorities for the tax years 2012 through 2015. In general, a TRS may perform non-customary services for customers, hold assets that DFT cannot hold directly and generally may engage in any real estate or non-real estate related business. A TRS is subject to corporate federal and state income taxes on its taxable income at regular statutory tax rates. For the years ended December 31, 2015 and 2013 , we incurred no income taxes. For the year ended December 31, 2014 , we incurred $0.1 million of income taxes. We account for income taxes using the asset and liability method under which deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Valuation allowances are provided if, based upon the weight of the available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. As of December 31, 2015 , the TRS had a deferred tax asset of $4.6 million , comprised entirely of its net operating loss carryforward, and a deferred tax liability of $2.3 million , primarily comprised of a temporary depreciation difference, resulting in a net deferred tax asset of $2.3 million . We have recorded a full valuation allowance for this net deferred tax asset as of December 31, 2015 due to the uncertainty of the realizability of this asset. Accordingly, for the year December 31, 2015 , we recorded a deferred income tax credit of $0.2 million to reverse the cumulative deferred tax expense recorded as of December 31, 2014 , described below. The net operating loss carryforward of $4.6 million described above will begin to expire in 2031 if not utilized by then. As of December 31, 2014 , the TRS had a deferred tax asset of $5.5 million , comprised entirely of its net operating loss carryforward, and a deferred tax liability of $6.1 million , primarily comprised of a temporary depreciation difference, resulting in a net deferred tax liability of $0.6 million . For the year December 31, 2014 , we recorded deferred income tax expense of $0.2 million related to this deferred tax liability. Redeemable Noncontrolling Interests – Operating Partnership / Redeemable Partnership Units Redeemable noncontrolling interests – operating partnership, as presented on DFT’s consolidated balance sheets, represent the limited partnership interests in the Operating Partnership (“OP units”) held by individuals and entities other than DFT. These interests are also presented on the Operating Partnership’s consolidated balance sheets, referred to as “redeemable partnership units.” Accordingly, the following discussion related to redeemable noncontrolling interests – operating partnership of DFT refers equally to redeemable partnership units of the Operating Partnership. Redeemable noncontrolling interests – operating partnership, which require cash payment, or allow settlement in shares, but with the ability to deliver the shares outside of the control of DFT, are reported outside of the permanent equity section of the consolidated balance sheets of DFT and the Operating Partnership. Redeemable noncontrolling interests – operating partnership are adjusted for income, losses and distributions allocated to OP units not held by DFT (normal noncontrolling interest accounting amount). Adjustments to redeemable noncontrolling interests – operating partnership are recorded to reflect increases or decreases in the ownership of the Operating Partnership by holders of OP units, including the redemptions of OP units for cash or in exchange for shares of DFT’s common stock. If such adjustments result in redeemable noncontrolling interests – operating partnership being recorded at less than the redemption value of the OP units, redeemable noncontrolling interests – operating partnership are further adjusted to their redemption value (see Note 9). Redeemable noncontrolling interests – operating partnership are recorded at the greater of the normal noncontrolling interest accounting amount or redemption value. The following is a summary of activity for redeemable noncontrolling interests – operating partnership for the years ended December 31, 2015 , 2014 and 2013 (dollars in thousands): OP Units Number Amount Balance at December 31, 2012 18,786,806 $ 453,889 Net income attributable to redeemable noncontrolling interests – operating partnership — 5,214 Distributions declared — (15,050 ) Redemption of operating partnership units (3,115,269 ) (75,600 ) Adjustments to redeemable noncontrolling interests – operating partnership — 18,791 Balance at December 31, 2013 15,671,537 $ 387,244 Net income attributable to redeemable noncontrolling interests – operating partnership — 18,704 Distributions declared — (22,831 ) Redemption of operating partnership units (234,300 ) (6,100 ) Adjustments to redeemable noncontrolling interests – operating partnership — 136,117 Balance at December 31, 2014 15,437,237 $ 513,134 Net loss attributable to redeemable noncontrolling interests – operating partnership — (5,993 ) Distributions declared — (26,513 ) Redemption of operating partnership units (363,674 ) (9,544 ) Adjustments to redeemable noncontrolling interests – operating partnership — 8,105 Balance at December 31, 2015 15,073,563 $ 479,189 The following is a summary of activity for redeemable partnership units for the years ended December 31, 2015 , 2014 and 2013 (dollars in thousands): OP Units Number Amount Balance at December 31, 2012 18,786,806 $ 453,889 Redemption of operating partnership units (3,115,269 ) (75,600 ) Adjustments to redeemable partnership units — 8,955 Balance at December 31, 2013 15,671,537 $ 387,244 Redemption of operating partnership units (234,300 ) (6,100 ) Adjustments to redeemable partnership units — 131,990 Balance at December 31, 2014 15,437,237 $ 513,134 Redemption of operating partnership units (363,674 ) (9,544 ) Adjustments to redeemable partnership units — (24,401 ) Balance at December 31, 2015 15,073,563 $ 479,189 Net income is allocated to controlling interests and redeemable

3. Real Estate Assets

3. Real Estate Assets	12 Months Ended
	Dec. 31, 2015
Real Estate [Abstract]
Real Estate Disclosure [Text Block]	Real Estate Assets The following is a summary of our properties as of December 31, 2015 (dollars in thousands): Property Location Land Buildings and Improvements Construction in Progress and Land Held for Development Total Cost ACC2 Ashburn, VA $ 2,500 $ 154,192 $ 156,692 ACC3 Ashburn, VA 1,071 95,977 97,048 ACC4 Ashburn, VA 6,600 538,652 545,252 ACC5 Ashburn, VA 6,443 298,768 305,211 ACC6 Ashburn, VA 5,518 216,697 222,215 ACC7 Phase I-II Ashburn, VA 4,876 167,766 172,642 VA3 Reston, VA 9,000 179,021 188,021 VA4 Bristow, VA 6,800 149,499 156,299 CH1 Elk Grove Village, IL 23,611 358,739 382,350 CH2 Phase I Elk Grove Village, IL 3,998 71,847 75,845 NJ1 Phase I Piscataway, NJ 3,584 73,221 76,805 SC1 Santa Clara, CA 20,202 432,557 452,759 94,203 2,736,936 — 2,831,139 Construction in progress and land held for development (1 ) 300,939 300,939 $ 94,203 $ 2,736,936 $ 300,939 $ 3,132,078 (1) Properties located in Ashburn, VA (ACC7 Phases III-IV and ACC8); Piscataway, NJ (NJ1 Phase II), Elk Grove Village, IL (CH2 Phases II-III and CH3) and Santa Clara, CA (SC2). In the fourth quarter of 2015, we determined that it was more likely than not that we would sell our NJ1 data center prior to the end of its previously estimated useful life. We believe that it is unlikely that we will develop NJ1 Phase II prior to the sale. In August 2015, we acquired two parcels of land totaling 9.7 acres for a total purchase price of $8.6 million . These parcels are adjacent to our CH1 data center in Elk Grove Village, Illinois and are being held for the future development of CH3. In February 2016, we acquired two parcels of undeveloped land in Ashburn, Virginia. One parcel is a 35.4 acre site that we purchased for $15.6 million , and the other parcel is an 8.6 acre site that we purchased for $4.6 million . These parcels are being held for future development of ACC9, ACC10 and either a powered base shell or build-to-suit data center. The following presents the major components of our properties and the useful lives over which they are depreciated. Component Component Life (years) Land N/A Building improvements 40 Electrical infrastructure—power distribution units 20 Electrical infrastructure—uninterrupted power supply 25 Electrical infrastructure—switchgear/transformers 30 Fire protection 40 Security systems 20 Mechanical infrastructure—heating, ventilating and air conditioning 20 Mechanical infrastructure—chiller pumps/building automation 25 Mechanical infrastructure—chilled water storage and pipes 30

4. Intangible Assets and Liabil

4. Intangible Assets and Liabilities (Notes)	12 Months Ended
	Dec. 31, 2015
Intangible Assets and Liabilities [Abstract]
Intangible Assets And Liabilities [Text Block]	Intangible Assets and Liabilities Leasing costs are classified as deferred costs and are amortized as amortization expense on a straight-line basis over the remaining life of the underlying leases. As of December 31, 2015 , these assets have a weighted average remaining life of 6.6 years with estimated future amortization as follows (in thousands): Year Ending December 31, 2016 $ 4,167 2017 3,864 2018 3,336 2019 2,374 2020 1,868 2021 and thereafter 4,936 $ 20,545 Lease intangible assets and liabilities are classified as lease contracts above and below market value, respectively, and amortized on a straight-line basis as decreases and increases, respectively, to rental revenue over the remaining term of the underlying leases. As of December 31, 2015 , our net lease intangible assets have a weighted average remaining life of 7.8 years for above market leases and 4.3 years for below market leases with estimated net future amortization (as an increase (decrease) to rental income) as follows (in thousands): Year Ending December 31, 2016 $ 464 2017 288 2018 56 2019 (421 ) 2020 (603 ) 2021 and thereafter (1,681 ) $ (1,897 ) Tenant origination costs are included in buildings and improvements in our accompanying consolidated balance sheets and are amortized as depreciation expense on a straight-line basis over the average remaining life of the underlying leases. As of December 31, 2015 , these assets have a weighted average remaining life of 2.6 years with estimated future amortization as follows (in thousands): Year Ending December 31, 2016 $ 1,243 2017 1,243 2018 746 $ 3,232

5. Leases (Notes)

5. Leases (Notes)	12 Months Ended
	Dec. 31, 2015
Leases [Abstract]
Leases of Lessor Disclosure [Text Block]	Leases For the years ended December 31, 2015 , 2014 and 2013 , the following customers comprised more than 10.0% of our consolidated revenues: Microsoft Facebook Rackspace Yahoo! Year ended December 31, 2015 25.2 % 16.9 % 11.3 % 8.9 % Year ended December 31, 2014 21.6 % 17.4 % 12.4 % 10.9 % Year ended December 31, 2013 17.8 % 19.2 % 11.6 % 13.0 % As of December 31, 2015 , these four customers accounted for $(5.2) million , $42.5 million , $36.4 million , and $7.5 million of deferred rent and $9.8 million , $6.8 million , $4.3 million , and $2.5 million of prepaid rents, respectively. As of December 31, 2014 , these four customers accounted for $(0.3) million , $43.6 million , $35.4 million , and $10.8 million of deferred rent and $8.3 million , $6.4 million , $0 , and $3.8 million of prepaid rents, respectively. We do not hold security deposits from these customers. The majority of our customers operate within the technology industry and, as such, their viability is subject to market fluctuations in that industry. As of December 31, 2015 , future minimum lease payments to be received under noncancelable operating leases are as follows for the years ending December 31 (in thousands): 2016 $ 323,322 2017 327,062 2018 301,662 2019 237,931 2020 186,848 2021 and thereafter 482,871 $ 1,859,696

6. Debt

6. Debt	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Debt Disclosure [Text Block]	Debt Debt Summary as of December 31, 2015 and December 31, 2014 ($ in thousands) December 31, 2015 December 31, 2014 Amounts (1) % of Total Rates Maturities (years) Amounts (1) Secured $ 115,000 9 % 2.0 % 2.2 $ 115,000 Unsecured 1,100,000 91 % 4.9 % 5.6 910,000 Total $ 1,215,000 100 % 4.6 % 5.3 $ 1,025,000 Fixed Rate Debt: Unsecured Notes due 2021 $ 600,000 49 % 5.9 % 5.7 $ 600,000 Unsecured Notes due 2023 (2) 250,000 21 % 5.6 % 7.5 — Fixed Rate Debt $ 850,000 70 % 5.8 % 6.2 $ 600,000 Floating Rate Debt: Unsecured Credit Facility — — % — % 2.4 60,000 Unsecured Term Loan 250,000 21 % 1.7 % 3.6 250,000 ACC3 Term Loan 115,000 9 % 2.0 % 2.2 115,000 Floating Rate Debt 365,000 30 % 1.8 % 3.1 425,000 Total $ 1,215,000 100 % 4.6 % 5.3 $ 1,025,000 (1) Principal amounts exclude deferred financing costs. (2) Principal amount shown excludes original issue discount of $1.9 million . Outstanding Indebtedness Unsecured Credit Facility Our Unsecured Credit Facility is an unsecured revolving credit facility with a total commitment of $700 million , which was increased from $560 million in July 2015. The Unsecured Credit Facility matures on May 13, 2018 and includes a one -year extension option, subject to the payment of an extension fee equal to 15 basis points on the total commitment in effect on such initial maturity date and certain other customary conditions. At our option, we may increase the total commitment under the facility to $800 million , if one or more lenders commit to being a lender for the additional amount and certain other customary conditions are met. We may also prepay the facility at any time, in whole or in part, without penalty or premium. We may elect to have borrowings under the facility bear interest at either LIBOR or a base rate, which is based on the lender's prime rate, in each case plus an applicable margin. Prior to our receiving an investment grade credit rating, the applicable margin added to LIBOR and the base rate is based on the table below. Applicable Margin Pricing Level Ratio of Total Indebtedness to Gross Asset Value LIBOR Rate Loans Base Rate Loans Level 1 Less than or equal to 35% 1.55 % 0.55 % Level 2 Greater than 35% but less than or equal to 40% 1.65 % 0.65 % Level 3 Greater than 40% but less than or equal to 45% 1.80 % 0.80 % Level 4 Greater than 45% but less than or equal to 52.5% 1.95 % 0.95 % Level 5 Greater than 52.5% 2.15 % 1.15 % The applicable margin is currently set at pricing level 1. The terms of the facility provide for the adjustment of the applicable margin from time to time according to the ratio of the Operating Partnership’s total indebtedness to gross asset value in effect from time to time. In the event we receive an investment grade credit rating, borrowings under the facility will bear interest based on the table below. Applicable Margin Credit Rating Level Credit Rating LIBOR Rate Loans Base Rate Loans Level 1 Greater than or equal to A- by S&P or A3 by Moody’s 0.875 % 0.00 % Level 2 Greater than or equal to BBB+ by S&P or Baa1 by Moody’s 0.925 % 0.00 % Level 3 Greater than or equal to BBB by S&P or Baa2 by Moody’s 1.05 % 0.05 % Level 4 Greater than or equal to BBB- by S&P or Baa3 by Moody’s 1.30 % 0.30 % Level 5 Less than BBB- by S&P or Baa3 by Moody’s 1.70 % 0.70 % Following the receipt of such investment grade rating, the terms of the facility provide for the adjustment of the applicable margin from time to time according to the rating then in effect. The facility is unconditionally guaranteed, jointly and severally, on a senior unsecured basis by DFT and all of the Operating Partnership’s subsidiaries that currently guaranty the obligations under the Unsecured Notes due 2021, listed below. The amount available for borrowings under the facility is determined according to a calculation comparing the value of certain unencumbered properties designated by the Operating Partnership at such time relative to the amount of the Operating Partnership's unsecured debt. Up to $35 million of the borrowings under the facility may be used for letters of credit. As of December 31, 2015 , a letter of credit of less than $0.1 million was outstanding under the facility. As of December 31, 2015 , there were no borrowings outstanding under this facility. As of February 19, 2016 , $40.0 million of borrowings were outstanding under this facility. The facility requires that DFT, the Operating Partnership and their subsidiaries comply with various covenants, including with respect to restrictions on liens, incurring indebtedness, making investments, effecting mergers and/or asset sales, and certain limits on dividend payments, distributions and purchases of DFT's stock. In addition, the facility imposes financial maintenance covenants relating to, among other things, the following matters: • unsecured debt not exceeding 60% of the value of unencumbered assets; • net operating income generated from unencumbered properties divided by the amount of unsecured debt being not less than 12.5% ; • total indebtedness not exceeding 60% of gross asset value; • fixed charge coverage ratio being not less than 1.70 to 1.00 ; and • tangible net worth being not less than $1.3 billion plus 80% of the sum of (i) net equity offering proceeds after March 21, 2012 and (ii) the value of equity interests issued in connection with a contribution of assets to the Operating Partnership or its subsidiaries. The facility includes customary events of default, the occurrence of which, following any applicable cure period, would permit the lenders to, among other things, declare the principal, accrued interest and other obligations of the Operating Partnership under the facility to be immediately due and payable. We were in compliance with all covenants under the facility as of December 31, 2015 . ACC3 Term Loan The ACC3 Term Loan is a $115 million term loan facility that is secured by our ACC3 data center facility and an assignment of the lease agreement between us and the customer of ACC3. The borrower, one of our subsidiaries, may elect to have borrowings under the ACC3 Term Loan bear interest at (i) LIBOR plus 1.55% or (ii) a base rate, which is based on the lender's prime rate, plus 0.55% . The interest rate is currently at LIBOR plus 1.55% . The ACC3 Term Loan matures on March 27, 2018 , and we may prepay the ACC3 Term Loan at any time, in whole or in part, without penalty or premium. The Operating Partnership has guaranteed the outstanding principal amount of the ACC3 Term Loan, plus interest and certain costs under the loan. The ACC3 Term Loan imposes financial maintenance covenants relating to, among other things, the following matters: • consolidated total indebtedness of the Operating Partnership not exceeding 60% of gross asset value of the Operating Partnership; • fixed charge coverage ratio of the Operating Partnership being not less than 1.70 to 1.00 ; • tangible net worth of the Operating Partnership being not less than $1.3 billion plus 80% of the sum of (i) net equity offering proceeds and (ii) the value of equity interests issued in connection with a contribution of assets to the Operating Partnership or its subsidiaries; and • debt service coverage ratio of the borrower not less than 1.50 to 1.00 . We were in compliance with all of the covenants under the loan as of December 31, 2015 . Unsecured Term Loan The Unsecured Term Loan is an unsecured term loan facility with a total commitment and amount outstanding of $250 million . The Unsecured Term Loan matures on July 21, 2019 , and we may prepay the facility at any time, in whole or in part, without penalty or premium. Under the terms of the Unsecured Term Loan, we may elect to have borrowings under the loan bear interest at either LIBOR or a base rate, which is based on the lender's prime rate, in each case plus an applicable margin. Prior to our receiving an investment grade credit rating, the applicable margin added to LIBOR and the base rate is based on the table below. Applicable Margin Pricing Level Ratio of Total Indebtedness to Gross Asset Value LIBOR Rate Loans Base Rate Loans Level 1 Less than or equal to 35% 1.50 % 0.50 % Level 2 Greater than 35% but less than or equal to 40% 1.60 % 0.60 % Level 3 Greater than 40% but less than or equal to 45% 1.75 % 0.75 % Level 4 Greater than 45% but less than or equal to 52.5% 1.90 % 0.90 % Level 5 Greater than 52.5% 2.10 % 1.10 % The applicable margin is currently set at pricing level 1. The terms of the Unsecured Term Loan also provide that, in the event we receive an investment grade credit rating, borrowings under the loan will bear interest based on the table below. Applicable Margin Credit Rating Level Credit Rating LIBOR Rate Loans Base Rate Loans Level 1 Greater than or equal to A- by S&P or A3 by Moody’s 0.825 % 0.00 % Level 2 Greater than or equal to BBB+ by S&P or Baa1 by Moody’s 0.875 % 0.00 % Level 3 Greater than or equal to BBB by S&P or Baa2 by Moody’s 1.00 % 0.00 % Level 4 Greater than or equal to BBB- by S&P or Baa3 by Moody’s 1.25 % 0.25 % Level 5 Less than BBB- by S&P or Baa3 by Moody’s 1.65 % 0.65 % Following the receipt of such investment grade rating, the terms of the loan provide for the adjustment of the applicable margin from time to time according to the rating then in effect. The Unsecured Term Loan is unconditionally guaranteed jointly and severally, on a senior unsecured basis by DFT and the direct and indirect subsidiaries of DFT that guaranty the obligations of the Unsecured Credit Facility. The Unsecured Term Loan requires that we comply with various covenants that are substantially the same as those applicable under the Unsecured Credit Facility, including with respect to restrictions on liens, incurring indebtedness, making investments, effecting mergers and/or asset sales, and certain restrictions on dividend payments . In addition, the Unsecured Term Loan imposes financial maintenance covenants substantially the same as those under the Unsecured Credit Facility relating to, among other things, the following matters: • unsecured debt not exceeding 60% of the value of unencumbered assets; • net operating income generated from unencumbered properties divided by the amount of unsecured debt being not less than 12.5% ; • total indebtedness not exceeding 60% of gross asset value; • fixed charge coverage ratio being not less than 1.70 to 1.00 ; and • tangible net worth being not less than $1.3 billion plus 80% of the sum of (i) net equity offering proceeds after March 21, 2012 and (ii) the value of equity interests issued in connection with a contribution of assets to the Operating Partnership or its subsidiaries after March 21, 2012. The Unsecured Term Loan includes customary events of default, the occurrence of which, following any applicable cure period, would permit the lenders to, among other things, declare the principal, accrued interest and other obligations under the loan to be immediately due and payable. We were in compliance with all of the covenants under the loan as of December 31, 2015 . Unsecured Notes due 2021 On September 24, 2013 , the Operating Partnership completed the sale of the Unsecured Notes due 2021, which represent $600 million of 5.875% senior unsecured notes due 2021. The Unsecured Notes due 2021 were issued at face value and mature on September 15, 2021 . We pay interest on the Unsecured Notes due 2021 semi-annually, in arrears, on March 15th and September 15th of each year. The Unsecured Notes due 2021 are unconditionally guaranteed, jointly and severally on a senior unsecured basis by DFT and certain of the Operating Partnership’s subsidiaries, including the subsidiaries that own the ACC2, ACC4, ACC5, ACC6, VA3, VA4, CH1, NJ1 and SC1 data centers and the SC2 land (collectively, the “Subsidiary Guarantors”), but excluding the subsidiaries that own the ACC3, ACC7 and CH2 data center facilities, the ACC8 land, our taxable REIT subsidiary, DF Technical Services, LLC and our property management subsidiary, DF Property Management LLC. The Unsecured Notes due 2021 rank (i) equally in right of payment with all of the Operating Partnership's existing and future senior unsecured indebtedness, (ii) senior in right of payment with all of its existing and future subordinated indebtedness, (iii) effectively subordinate to any of the Operating Partnership's existing and future secured indebtedness and (iv) effectively junior to any liabilities of any subsidiaries of the Operating Partnership that do not guarantee the Unsecured Notes due 2021. The guarantees of the Unsecured Notes due 2021 by DFT and the Subsidiary Guarantors rank (i) equally in right of payment with such guarantor's existing and future senior unsecured indebtedness, (ii) senior in right of payment with all of such guarantor's existing and future subordinated indebtedness and (iii) effectively subordinate to any of such guarantor's existing and future secured indebtedness. At any time prior to September 15, 2016, the Operating Partnership may redeem the Unsecured Notes due 2021, in whole or in part, at a price equal to the sum of (i) 100% of the principal amount of the Unsecured Notes due 2021 to be redeemed, plus (ii) a make-whole premium and accrued and unpaid interest. The Unsecured Notes due 2021 may be redeemed at the Operating Partnership's option, in whole or in part, at any time, on and after September 15, 2016 at the following redemption prices (expressed as percentages of the principal amount thereof) if redeemed during the 12-month period commencing September 15 of the years indicated below, in each case together with accrued and unpaid interest to the date of redemption: Year Redemption Price 2016 104.406 % 2017 102.938 % 2018 101.469 % 2019 and thereafter 100.000 % If there is a change of control (as defined in the indenture governing the Unsecured Notes due 2021) of the Operating Partnership or DFT, we must offer to purchase the Unsecured Notes due 2021 at a price equal to 101% of the principal amount thereof, plus accrued and unpaid interest. In addition, in certain circumstances we may be required to use the net proceeds of asset sales to purchase a portion of the Unsecured Notes due 2021 at 100% of the principal amount thereof, plus accrued and unpaid interest. The Unsecured Notes due 2021 have certain covenants limiting or prohibiting the ability of the Operating Partnership and certain of its subsidiaries from, among other things, (i) incurring secured or unsecured indebtedness, (ii) entering into sale and leaseback transactions, (iii) making certain dividend payments, distributions, purchases of DFT's common stock and investments, (iv) entering into transactions with affiliates, (v) entering into agreements limiting the ability to make certain transfers and other payments from subsidiaries, (vi) engaging in sales of assets or (vii) engaging in certain mergers, consolidations or transfers/sales of all or substantially all assets. However, DFT may pay the minimum dividend necessary to meet its REIT income distribution requirements. The Unsecured Notes due 2021 also require the Operating Partnership and the Subsidiary Guarantors to maintain total unencumbered assets of at least 150% of their unsecured debt on a consolidated basis. The Unsecured Notes due 2021 also have customary events of default, including, but not limited to, nonpayment, breach of covenants, and payment or acceleration defaults in certain other indebtedness of ours or certain of our subsidiaries. Upon an event of default, the holders of the Unsecured Notes due 2021 or the trustee may declare the Unsecured Notes due 2021 due and immediately payable. We were in compliance with all covenants under the Unsecured Notes due 2021 as of December 31, 2015 . Unsecured Notes due 2023 On June 9, 2015 , the Operating Partnership completed the sale of the Unsecured Notes due 2023, which represent $250 million of 5.625% senior unsecured notes due 2023. The Unsecured Notes due 2023 were issued at 99.205% of par and mature on June 15, 2023 . We will pay interest on the Unsecured Notes due 2023 semi-annually, in arrears, on June 15th and December 15th of each year, beginning December 15, 2015 . The Unsecured Notes due 2023 are unconditionally guaranteed, jointly and severally on a senior unsecured basis by DFT and the same Subsidiary Guarantors as those that guaranty the Unsecured Notes due 2021. The ranking of the Unsecured Notes due 2023 and the guarantees of these notes are the same as the ranking of the Unsecured Notes due 2021 and the guarantee of those notes. At any time prior to June 15, 2018, the Operating Partnership may redeem the Unsecured Notes due 2023, in whole or in part, at a price equal to the sum of (i) 100% of the principal amount of the Unsecured Notes due 2023 to be redeemed, plus (ii) a make-whole premium and accrued and unpaid interest. The Unsecured Notes due 2023 may be redeemed at the Operating Partnership's option, in whole or in part, at any time, on and after June 15, 2018 at the following redemption prices (expressed as percentages of the principal amount thereof) if redeemed during the 12-month period commencing June 15 of the years indicated below, in each case together with accrued and unpaid interest to the date of redemption: Year Redemption Price 2018 104.219 % 2019 102.813 % 2020 101.406 % 2021 and thereafter 100.000 % If there is a change of control (as defined in the indenture governing the Unsecured Notes due 2023) of the Operating Partnership or DFT, we must offer to purchase the Unsecured Notes due 2023 at a price equal to 101% of the principal amount thereof, plus accrued and unpaid interest. In addition, in certain circumstances we may be required to use the net proceeds of asset sales to purchase a portion of the Unsecured Notes due 2023 at 100% of the principal amount thereof, plus accrued and unpaid interest. The Unsecured Notes due 2023 have certain covenants limiting or prohibiting the ability of the Operating Partnership and certain of its subsidiaries from, among other things, (i) incurring secured or unsecured indebtedness, (ii) entering into sale and leaseback transactions, (iii) making certain dividend payments, distributions, purchases of DFT's common stock and investments, (iv) entering into transactions with affiliates, (v) entering into agreements limiting the ability to make certain transfers and other payments from subsidiaries, (vi) engaging in sales of assets or (vii) engaging in certain mergers, consolidations or transfers/sales of all or substantially all assets. However, DFT may pay the minimum dividend necessary to meet its REIT income distribution requirements. The Unsecured Notes due 2023 also require the Operating Partnership and the Subsidiary Guarantors to maintain total unencumbered assets of at least 150% of their unsecured debt on a consolidated basis. The Unsecured Notes due 2023 also have customary events of default, including, but not limited to, nonpayment, breach of covenants, and payment or acceleration defaults in certain other indebtedness of ours or certain of our subsidiaries. Upon an event of default, the holders of the Unsecured Notes due 2023 or the trustee may declare the Unsecured Notes due 2023 due and immediately payable. We were in compliance with all covenants under the Unsecured Notes due 2023 as of December 31, 2015 . A summary of our debt repayment schedule as of December 31, 2015 is as follows: Debt Maturity as of December 31, 2015 ($ in thousands) Year Fixed Rate (1) Floating Rate (1) Total (1) % of Total Rates 2016 $ — $ 3,750 (4) $ 3,750 0.3 % 2.0 % 2017 — 8,750 (4) 8,750 0.7 % 2.0 % 2018 — 102,500 (4) 102,500 8.4 % 2.0 % 2019 — 250,000 (5) 250,000 20.6 % 1.7 % 2020 — — — — % — % 2021 600,000 (2) — 600,000 49.4 % 5.9 % 2022 — — — — % — % 2023 250,000 (3) — 250,000 20.6 % 5.6 % Total $ 850,000 $ 365,000 $ 1,215,000 100 % 4.6 % (1) Principal amounts exclude deferred financing costs. (2) The 5.875% Unsecured Notes due 2021 mature on September 15, 2021 . (3) The 5.625% Unsecured Notes due 2023 mature on June 15, 2023 . Principal amount excludes original issue discount of $1.9 million as of December 31, 2015 . (4) The ACC3 Term Loan matures on March 27, 2018 with no extension option. Quarterly principal payments of $1.25 million begin on April 1, 2016 , increase to $2.5 million on April 1, 2017 and continue through maturity. (5) The Unsecured Term Loan matures on July 21, 2019 with no extension option.

7. Related Party Transactions (

7. Related Party Transactions (Notes)	12 Months Ended
	Dec. 31, 2015
Related Party Transactions Disclosure [Text Block]	Related Party Transactions For the years ended December 31, 2015 , 2014 and 2013 , we incurred $0 , $0.1 million and $0.3 million of cost, respectively, to charter an aircraft for business travel that is owned by our former CEO. For the years ended December 31, 2015 , 2014 and 2013 , we incurred $0 , $0 and $0.1 million of expenses for personal travel of our former CEO in lieu of his annual salary under the terms of his employment agreement. Effective February 5, 2013, we no longer reimbursed our former CEO for personal travel in lieu of salary. We lease space for our headquarters building from an affiliate of our Chairman of the Board and our former CEO. Rent expense was $0.4 million for each of the years ended December 31, 2015 , 2014 and 2013 . In February 2016, we acquired two parcels of undeveloped land in Ashburn, Virginia, from entities controlled by our Chairman of the Board and our former CEO. These two parcels were under contract as of December 31, 2015 . One parcel is a 35.4 acre site that is adjacent to the Ashburn Corporate Center, where our ACC2, ACC3, ACC4, ACC5, ACC6 and ACC7 data center facilities are located, which we purchased for $15.6 million . The sole managers of the entity that owned this site are a limited liability company owned solely by our Chairman of the Board, which also owns approximately 7% of the seller, and a limited liability company owned solely by our former CEO which also owns approximately 1% of the seller. The other parcel is an 8.6 acre site that is part of the Ashburn Corporate Center and adjacent to our ACC4 and ACC7 data center facilities, which we purchased for $4.6 million . Our Chairman of the Board and our former CEO are the sole managers of the limited liability company that manages the entity that owned this site. Our Chairman of the Board directly and indirectly owns approximately 23% of the seller, and our former CEO directly and indirectly owns approximately 18% of the seller. In addition, Frederic V. Malek, one of our independent directors, is a non-managing member of the entity that owns this site. Mr. Malek’s sole interest in this entity is the ownership of an approximately 4% non-managing membership interest; he is neither an employee nor an executive officer of this entity. The purchase price for each site was based on an appraisal prepared for the Audit Committee of our Board of Directors by an independent appraisal firm.

8. Commitments and Contingencie

8. Commitments and Contingencies	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies Disclosure [Text Block]	Commitments and Contingencies We are involved from time to time in various legal proceedings, lawsuits, examinations by various tax authorities and claims that have arisen in the ordinary course of business. We currently believe that the resolution of such matters will not have a material adverse effect on our financial condition or results of operations. Contracts related to the development of the ACC7 Phase II, ACC7 Phase III, CH2 Phase II and CH2 Phase III data centers were in place as of December 31, 2015 . These contracts are cost plus in nature whereby the contract sum is the aggregate cost of the actual work performed and equipment purchased plus a contractor fee. Control estimates, which are adjusted from time to time to reflect any contract changes, are estimates of the total contract cost at completion. As of December 31, 2015 the ACC7 Phase II control estimate was $43.1 million of which $40.7 million had been incurred. An additional $1.1 million has been committed under this contract as of December 31, 2015 . As of December 31, 2015 the ACC7 Phase III control estimate was $75.0 million of which $53.4 million had been incurred. An additional $10.5 million has been committed under this contract as of December 31, 2015 . As of December 31, 2015 , the CH2 Phase II control estimate was $17.8 million of which $10.6 million has been incurred. An additional $3.7 million has been committed under this contract as of December 31, 2015 . As of December 31, 2015 , the CH2 Phase III control estimate was $66.6 million of which $15.1 million has been incurred. An additional $18.8 million has been committed under this contract as of December 31, 2015 . Concurrent with DFT’s October 2007 initial public offering, we entered into tax protection agreements with some of the contributors of the initial properties including our Chairman of the Board and our former CEO. Pursuant to the terms of these agreements, if we dispose of any interest in the initial contributed properties that generates more than a certain allowable amount of built-in gain for the contributors, as a group, in any single year through 2017, we will indemnify the contributors for a portion of the tax liabilities incurred with respect to the amount of built-in gain and tax liabilities incurred as a result of the reimbursement payment. The amount of initial built-in gain that can be recognized as of January 1, 2016 without triggering the tax protection provisions is approximately 90% of the initial built in gain of $667 million (unaudited) or $600 million (unaudited). This percentage increases each year by 10% , accumulating to 100% in 2017. As of December 31, 2015 , none of the tax protection provisions have been triggered and no liability has been recorded on our consolidated balance sheet. If, as of January 1, 2016, the tax protection provisions were triggered, we would not be liable for protection on the taxes related to the built-in gain. Additionally, pursuant to the terms of these agreements, we must provide an opportunity for certain of the contributors of the initial properties to guarantee a secured loan and, if we fail to do so, we could be liable for protection on the taxes related to approximately $97 million (unaudited) of remaining minimum liability. The amount of our liability for protection on taxes could be based on the highest federal, state and local capital gains tax rates of the applicable contributor. Any sale by the Company that requires payments to any of DFT’s executive officers or directors pursuant to these agreements requires the approval of at least 75% of the disinterested members of DFT’s Board of Directors.

9. Redeemable noncontrolling in

9. Redeemable noncontrolling interests operating partnership / Redeemable partnership units	12 Months Ended
	Dec. 31, 2015
Redeemable noncontrolling interests – operating partnership / Redeemable partnership units [Abstract]
Redeemable noncontrolling interests – operating partnership / Redeemable partnership units [Text Block]	Redeemable noncontrolling interests – operating partnership / Redeemable partnership units Redeemable noncontrolling interests – operating partnership, as presented in DFT’s accompanying consolidated balance sheets, represent the OP units held by individuals and entities other than DFT. These interests are also presented in the Operating Partnership’s consolidated balance sheets, referred to as “redeemable partnership units.” Accordingly, the following discussion related to redeemable noncontrolling interests – operating partnership of DFT refers equally to redeemable partnership units of the Operating Partnership. The redemption value of redeemable noncontrolling interests – operating partnership as of December 31, 2015 and December 31, 2014 was $479.2 million and $513.1 million , respectively, based on the closing share price of DFT’s common stock of $31.79 and $33.24 , respectively, on those dates. Holders of OP units are entitled to receive distributions in a per unit amount equal to the per share dividends made with respect to each share of DFT’s common stock, if and when DFT’s Board of Directors declares such a dividend. Holders of OP units have the right to tender their units for redemption, in an amount equal to the fair market value of DFT’s common stock. DFT may elect to redeem tendered OP units for cash or for shares of DFT’s common stock. During the years ended December 31, 2015 , 2014 and 2013 OP unitholders redeemed a total of 363,674 , 234,300 , and 3,115,269 OP units, respectively, in exchange for an equal number of shares of common stock. See Note 2.

10. Preferred Stock

10. Preferred Stock	12 Months Ended
	Dec. 31, 2015
Preferred Stock [Abstract]
Preferred Stock [Text Block]	Preferred Stock Series A Preferred Stock In October 2010, DFT issued 7,400,000 shares of 7.875% Series A Cumulative Redeemable Perpetual Preferred Stock (“Series A Preferred Stock”) for $185.0 million in an underwritten public offering. The liquidation preference on the Series A Preferred Stock is $25 per share and dividends are scheduled quarterly. For each share of Series A Preferred Stock issued by DFT, the Operating Partnership issued a preferred unit equivalent to DFT with the same terms. For the year ended December 31, 2015 , DFT declared and paid the following cash dividends on its Series A Preferred Stock, of which the OP paid equivalent distributions on its preferred units: Record Date Payment Date Cash Dividend Ordinary Taxable Dividend (Unaudited) Nontaxable Return of Capital Distributions (Unaudited) 4/2/2015 4/15/2015 $ 0.4921875 $ 0.4921875 $ 0.00 7/2/2015 7/15/2015 0.4921875 0.4921875 0.00 10/2/2015 10/15/2015 0.4921875 0.4921875 0.00 12/30/2015 1/15/2016 0.4921875 0.4921875 0.00 $ 1.9687500 $ 1.9687500 $ 0.00 For the year ended December 31, 2014 , DFT declared and paid the following cash dividends on its Series A Preferred Stock, of which the OP paid equivalent distributions on its preferred units: Record Date Payment Date Cash Dividend Ordinary Taxable Dividend (Unaudited) Nontaxable Return of Capital Distributions (Unaudited) 4/4/2014 4/15/2014 $ 0.4921875 $ 0.4921875 $ 0.00 7/3/2014 7/15/2014 0.4921875 0.4921875 0.00 10/3/2014 10/15/2014 0.4921875 0.4921875 0.00 12/30/2014 1/15/2015 0.4921875 0.4921875 0.00 $ 1.9687500 $ 1.9687500 $ 0.00 For the year ended December 31, 2013 , DFT declared and paid the following cash dividends on its Series A Preferred Stock, of which the OP paid equivalent distributions on its preferred units: Record Date Payment Date Cash Dividend Ordinary Taxable Dividend (Unaudited) Nontaxable Return of Capital Distributions (Unaudited) 4/5/2013 4/15/2013 $ 0.4921875 $ 0.4921875 $ 0.00 7/5/2013 7/15/2013 0.4921875 0.4921875 0.00 10/4/2013 10/15/2013 0.4921875 0.4921875 0.00 12/27/2013 1/15/2014 0.4921875 0.4921875 0.00 $ 1.9687500 $ 1.9687500 $ 0.00 Effective October 15, 2015 , we may, at our option, redeem the Series A Preferred Stock, in whole, at any time, or in part, from time to time, for cash at a redemption price of $25 per share, plus any accrued and unpaid dividends to, but not including, the date of redemption. If, at any time following a change of control, the Series A Preferred Stock is not listed on the NYSE or quoted on NASDAQ (or listed or quoted on a successor exchange or quotation system), holders will be entitled to receive dividends at an increased rate of 11.875% , and we will have the option to redeem the Series A Preferred Stock, in whole but not in part, within 90 days after the first date on which both the change of control has occurred and the Series A Preferred Stock is not so listed or quoted, for cash at $25 per share, plus accrued and unpaid dividends (whether or not declared) to, but not including, the redemption date. Series B Preferred Stock In March 2011 and January 2012, DFT issued an aggregate of 6,650,000 shares of 7.625% Series B Cumulative Redeemable Perpetual Preferred Stock (“Series B Preferred Stock”) for $166.3 million in underwritten public offerings. The liquidation preference on the Series B Preferred Stock is $25 per share and dividends are scheduled quarterly. For each share of Series B Preferred Stock issued by DFT, the Operating Partnership issued a preferred unit equivalent to DFT with the same terms. For the year ended December 31, 2015 , DFT declared and paid the following cash dividends on its Series B Preferred Stock, of which the OP paid equivalent distributions on its preferred units: Record Date Payment Date Cash Dividend Ordinary Taxable Dividend (Unaudited) Nontaxable Return of Capital Distributions (Unaudited) 4/2/2015 4/15/2015 $ 0.4765625 $ 0.4765625 $ 0.00 7/2/2015 7/15/2015 0.4765625 0.4765625 0.00 10/2/2015 10/15/2015 0.4765625 0.4765625 0.00 12/30/2015 1/15/2016 0.4765625 0.4765625 0.00 $ 1.9062500 $ 1.9062500 $ 0.00 For the year ended December 31, 2014 , DFT declared and paid the following cash dividends on its Series B Preferred Stock, of which the OP paid equivalent distributions on its preferred units: Record Date Payment Date Cash Dividend Ordinary Taxable Dividend (Unaudited) Nontaxable Return of Capital Distributions (Unaudited) 4/4/2014 4/15/2014 $ 0.4765625 $ 0.4765625 $ 0.00 7/3/2014 7/15/2014 0.4765625 0.4765625 0.00 10/3/2014 10/15/2014 0.4765625 0.4765625 0.00 12/30/2014 1/15/2015 0.4765625 0.4765625 0.00 $ 1.9062500 $ 1.9062500 $ 0.00 For the year ended December 31, 2013 , DFT declared and paid the following cash dividends on its Series B Preferred Stock, of which the OP paid equivalent distributions on its preferred units: Record Date Payment Date Cash Dividend Ordinary Taxable Dividend (Unaudited) Nontaxable Return of Capital Distributions (Unaudited) 4/5/2013 4/15/2013 $ 0.4765625 $ 0.4765625 $ 0.00 7/5/2013 7/15/2013 0.4765625 0.4765625 0.00 10/4/2013 10/15/2013 0.4765625 0.4765625 0.00 12/27/2013 1/15/2014 0.4765625 0.4765625 0.00 $ 1.9062500 $ 1.9062500 $ 0.00 Except in instances relating to preservation of DFT's qualification as a REIT or pursuant to the special optional redemption right and conversion right discussed below, the Series B Preferred Stock is not redeemable prior to March 15, 2016 or convertible at any time. On and after March 15, 2016 , we may, at our option, redeem the Series B Preferred Stock, in whole, at any time, or in part, from time to time, for cash at a redemption price of $25 per share, plus any accrued and unpaid dividends to, but not including, the date of redemption. Upon the occurrence of a change of control, we have a special optional redemption right that enables us to redeem the Series B Preferred Stock within 120 days after the first date on which a change of control has occurred resulting in neither DFT nor the surviving entity having a class of common shares listed on the NYSE, NYSE Amex or NASDAQ. For this special redemption right, the redemption price is $25 per share in cash, plus accrued and unpaid dividends (whether or not declared) to, but not including, the redemption date. Upon the occurrence of a change of control that results in neither DFT nor the surviving entity having a class of common shares listed on the NYSE, NYSE Amex or NASDAQ, the holder will have the right (subject to our special optional redemption right to redeem the Series B Preferred Stock) to convert some or all of the Series B Preferred Stock into a number of shares of DFT's common stock equal to the lesser of (A) the quotient obtained by dividing (i) the sum of (x) $25.00, plus (y) an amount equal to any accrued and unpaid dividends, whether or not declared, to but not including, the date of conversion (unless the date of conversion is after a record date for a Series B Preferred Stock dividend payment and prior to the corresponding Series B Preferred Stock dividend payment date, in which case no additional amount for such accrued and unpaid dividend will be included in this quotient), by (ii) the price of DFT's common stock, and (B) 2.105 (the Share Cap), subject to certain adjustments and provisions for the receipt of alternative consideration of equivalent value.

11. Stockholders Equity of the

11. Stockholders Equity of the REIT and Partners Capital of the OP	12 Months Ended
	Dec. 31, 2015
Stockholders’ Equity of the REIT and Partners’ Capital of the OP [Abstract]
Stockholders' Equity Of The REIT And Partners' Capital Of The OP [Text Block]	Stockholders’ Equity of DFT and Partners’ Capital of the OP During the years ended December 31, 2015 , 2014 and 2013 : • DFT issued an aggregate of 565,162 , 163,187 and 216,209 shares of common stock, respectively, in connection with our annual grant of restricted stock to employees, the hiring of new employees and grants and retainers for our Board of Directors. The OP issued an equivalent number of units to the REIT. • OP unitholders redeemed a total of 363,674 , 234,300 and 3,115,269 OP units, respectively, in exchange for an equal number of shares of DFT’s common stock. For the year ended December 31, 2015 , DFT declared and paid the following cash dividends totaling $1.73 per share on its common stock, of which the OP paid equivalent distributions on OP units: Record Date Payment Date Cash Dividend Ordinary Taxable Dividend (Unaudited) Nontaxable Return of Capital Distributions (Unaudited) 04/02/2015 04/15/2015 $ 0.42 $ 0.42 $ — 07/02/2015 07/15/2015 0.42 0.42 — 10/02/2015 10/15/2015 0.42 0.42 — 12/30/2015 01/16/2016 0.47 0.33 — $ 1.73 $ 1.59 $ — Of the $0.47 dividend paid in January 2016, $0.14 (unaudited) will be included in 2016 taxable common dividends. For the year ended December 31, 2014 , DFT declared and paid the following cash dividends totaling $1.47 per share on its common stock, of which the OP paid equivalent distributions on OP units: Record Date Payment Date Cash Dividend Ordinary Taxable Dividend (Unaudited) Nontaxable Return of Capital Distributions (Unaudited) 04/04/2014 04/15/2014 $ 0.35 $ 0.35 $ — 07/03/2014 07/15/2014 0.35 0.35 — 10/03/2014 10/15/2014 0.35 0.35 — 12/30/2014 01/15/2015 0.42 0.39 — $ 1.47 $ 1.44 $ — Of the $0.42 dividend paid in January 2015, $0.03 (unaudited) was included in 2015 taxable common dividends. For the year ended December 31, 2013, DFT declared and paid the following cash dividends totaling $0.95 per share on its common stock, of which the OP paid equivalent distributions on OP units: Record Date Payment Date Cash Dividend Ordinary Taxable Dividend (Unaudited) Nontaxable Return of Capital Distributions (Unaudited) 04/05/2013 04/15/2013 $ 0.20 $ 0.172 $ 0.028 07/05/2013 07/15/2013 0.25 0.214 0.036 10/04/2013 10/15/2013 0.25 0.214 0.036 12/27/2013 01/15/2014 0.25 — 0.000 $ 0.95 $ 0.600 $ 0.100 Of the $0.25 dividend paid in January 2014, $0.25 (unaudited) was included in 2014 taxable common dividends. In September 2013, the Board of Directors approved a common stock repurchase program to acquire up to $122.2 million of DFT's common shares. Under this program, which expired on December 31, 2014 , DFT repurchased none of its common stock. In December 2014, the Board of Directors approved a common stock repurchase program to acquire up to $120.0 million of DFT's common shares in 2015. Under this program, which expired on December 31, 2015 , DFT repurchased 1,002,610 shares of its common stock totaling $31.9 million . All repurchased shares were retired immediately, and the Operating Partnership retired an equivalent number of units.

12. Equity Compensation Plan

12. Equity Compensation Plan	12 Months Ended
	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Disclosure of Compensation Related Costs, Share-based Payments [Text Block]	Equity Compensation Plan In May 2011, our Board of Directors adopted the 2011 Equity Incentive Plan (the “2011 Plan”) following approval from our stockholders. The 2011 Plan is administered by the Compensation Committee of our Board of Directors. The 2011 Plan allows us to provide equity-based compensation to our personnel and directors in the form of stock options, stock appreciation rights, dividend equivalent rights, restricted stock, restricted stock units, performance-based awards, unrestricted stock, long term incentive units (“LTIP units”) and other awards. The 2011 Plan authorizes a maximum aggregate of 6,300,000 share equivalents be reserved for future issuances. In addition, shares that were awarded under our 2007 Equity Compensation Plan (the “2007 Plan”) that subsequently become available due to forfeitures of such awards are available for issuance under the 2011 Plan. The 2011 Plan provides that awards can no longer be made under the 2007 Plan. Furthermore, under the 2011 Plan, shares of common stock that are subject to awards of options or stock appreciation rights will be counted against the 2011 Plan share limit as one share for every one share subject to the award. Any shares of stock that are subject to awards other than options or stock appreciation rights shall be counted against the 2011 Plan share limit as 2.36 shares for every one share subject to the award. As of December 31, 2015 , 3,247,727 share equivalents were issued under the 2011 Plan, and the maximum aggregate amount of share equivalents remaining available for future issuance was 3,052,273 . Restricted Stock Restricted stock awards vest over specified periods of time as long as the employee remains employed with the Company. The following table sets forth the number of unvested shares of restricted stock and the weighted average fair value of these shares at the date of grant: Shares of Restricted Stock Weighted Average Fair Value at Date of Grant Unvested balance at December 31, 2012 297,919 $ 22.31 Granted 203,241 $ 22.82 Vested (162,353 ) $ 21.73 Forfeited (34,843 ) $ 22.86 Unvested balance at December 31, 2013 303,964 $ 22.89 Granted 149,608 $ 25.63 Vested (125,798 ) $ 23.02 Forfeited (3,785 ) $ 23.98 Unvested balance at December 31, 2014 323,989 $ 24.10 Granted 171,475 $ 32.12 Vested (138,585 ) $ 23.87 Forfeited (7,737 ) $ 28.71 Unvested balance at December 31, 2015 349,142 $ 28.02 During the years ended December 31, 2015 , 2014 and 2013 , we issued 171,475 , 149,608 and 203,241 shares of restricted stock, respectively, which had an aggregate value of $5.5 million , $3.8 million and $4.6 million , on the respective grant dates. These amounts will be amortized to expense over the respective vesting periods, which are typically three years. Also during the years ended December 31, 2015 , 2014 and 2013 , 138,585 , 125,798 and 162,353 shares of restricted stock vested, respectively, at an intrinsic value of $4.3 million , $3.4 million and $3.8 million on their respective vesting dates. As of December 31, 2015 , total unearned compensation on restricted stock was $6.2 million , and the weighted average vesting period was 1.0 year . Stock Options Stock option awards are granted with an exercise price equal to the closing market price of DFT’s common stock at the date of grant and vest over specified periods of time as long as the employee remains employed with the Company. All shares to be issued upon option exercises will be newly issued shares and the options have 10-year contractual terms. During the year ended December 31, 2015 , no options were granted to employees. A summary of our stock option activity under the applicable equity incentive plan for the years ended December 31, 2015 , 2014 and 2013 is presented in the tables below. Number of Options Weighted Average Exercise Price Under option, December 31, 2012 2,076,781 $ 15.17 Granted 374,214 $ 22.62 Exercised (250,472 ) $ 6.83 Forfeited (100,613 ) $ 22.83 Under option, December 31, 2013 2,099,910 $ 17.13 Granted — $ — Exercised (507,056 ) $ 10.95 Forfeited — $ — Under option, December 31, 2014 1,592,854 $ 19.09 Granted — $ — Exercised (362,642 ) $ 21.87 Forfeited — $ — Under option, December 31, 2015 1,230,212 $ 18.28 Shares Subject to Option Total Unearned Compensation Weighted Average Vesting Period Weighted Average Remaining Contractual Term As of December 31, 2013 2,099,910 $ 1.9 million 0.8 years 6.9 years As of December 31, 2014 1,592,854 $ 0.7 million 0.5 years 6.2 years As of December 31, 2015 1,230,212 $ 0.1 million 0.2 years 4.9 years The following table sets forth the number of unvested options as of December 31, 2015 , 2014 and 2013 and the weighted average fair value of these options at the grant date. Number of Options Weighted Average Fair Value at Date of Grant Unvested balance at December 31, 2012 809,991 $ 6.96 Granted 374,214 $ 4.75 Vested (399,481 ) $ 7.34 Forfeited (100,613 ) $ 5.55 Unvested balance at December 31, 2013 684,111 $ 5.73 Granted — $ — Vested (381,787 ) $ 6.28 Forfeited — $ — Unvested balance at December 31, 2014 302,324 $ 5.05 Granted — $ — Vested (263,553 ) $ 5.10 Forfeited — $ — Unvested balance at December 31, 2015 38,771 $ 4.75 The following tables set forth the number of exercisable options as of December 31, 2015 , 2014 and 2013 and the weighted average fair value and exercise price of these options at the grant date. Number of Options Weighted Average Fair Value at Date of Grant Options Exercisable at December 31, 2012 1,266,790 $ 3.52 Vested 399,481 $ 7.34 Exercised (250,472 ) $ 2.35 Options Exercisable at December 31, 2013 1,415,799 $ 4.81 Vested 381,787 $ 6.28 Exercised (507,056 ) $ 3.54 Options Exercisable at December 31, 2014 1,290,530 $ 5.74 Vested 263,553 $ 5.10 Exercised (362,642 ) $ 6.34 Options Exercisable at December 31, 2015 1,191,441 $ 5.41 Exercisable Options Intrinsic Value Weighted Average Exercise Price Weighted Average Remaining Contractual Term As of December 31, 2013 1,415,799 $ 14.7 million $ 14.33 6.1 years As of December 31, 2014 1,290,530 $ 19.3 million $ 18.27 5.8 years As of December 31, 2015 1,191,441 $ 16.3 million $ 18.14 4.9 years The intrinsic value of stock options exercised during the years ended December 31, 2015 , 2014 and 2013 was $3.7 million , $7.7 million and $4.5 million , respectively. The fair value of each option award is estimated on the date of grant using a Black-Scholes option valuation model. Expected volatility used in the Black-Scholes model is based on DFT’s historical volatility. The risk-free rate for periods within the contractual life of the option is based on the U.S. Treasury yield curve in effect at the time of grant. The following table summarizes the assumptions used to value the stock options granted and the fair value of these options granted during the year ended December 31, 2013 . No stock options were granted during the years ended December 31, 2015 and 2014 . 2013 Number of options granted 374,214 Exercise price $ 22.62 Expected term (in years) 5 Expected volatility 34 % Expected annual dividend 4 % Risk-free rate 0.83 % Fair value at date of grant $1.8 million Performance Units Performance unit awards are awarded to certain executive employees and have a three calendar-year performance period with no dividend rights. Performance units will be settled in common shares following the performance period as long as the employee remains employed with us on the vesting date, which is the March 1st date following the last day of the applicable performance period. Performance units are valued using a Monte Carlo simulation and are amortized over the three year vesting period from the grant date to the vesting date. The number of common shares settled could range from 0% to 300% . For performance unit award grants prior to 2014, the vesting amount is dependent on DFT’s total stockholder return compared to the MSCI US REIT index over the three calendar-year performance period. For performance unit grants awarded in 2014 and 2015, one-half of the recipient's performance unit award is dependent on DFT’s total stockholder return compared to the MSCI US REIT index over the three calendar-year performance period. The other half of the performance unit award is dependent on DFT’s total stockholder return compared to an index of five comparable publicly traded data center companies over the three calendar-year performance period. For performance unit grants awarded in 2013, the entire award is dependent on DFT’s total stockholder return compared to the MSCI US REIT index over the three calendar-year performance period. The following table summarizes the assumptions used to value, and the resulting fair and maximum values of, the performance units granted during the years ended December 31, 2015 , 2014 and 2013 . 2015 2014 2013 Number of performance units granted 48,674 110,441 60,468 Expected volatility 24 % 30 % 33 % Expected annual dividend 5 % 5 % 4 % Risk-free rate 1.06 % 0.74 % 0.40 % Performance unit fair value at date of grant $ 38.34 $ 33.50 $ 25.59 Total grant fair value at date of grant $1.9 million $3.7 million $1.5 million Maximum value of grant on vesting date based on closing price of DFT's stock at the date of grant $4.7 million $8.5 million $4.1 million During the year ended December 31, 2015 , 4,225 performance units were forfeited with a weighted average fair value of $36.30 per unit. During the year ended December 31, 2014 , no performance units were forfeited. During the year ended December 31, 2013 , 22,091 performance units were forfeited with a weighted average fair value of $26.93 per unit. As of December 31, 2015 , total unearned compensation on outstanding performance units was $1.8 million . For the performance units granted in 2013, based on DFT’s total stockholder return compared to the MSCI US REIT index return for the period from January 1, 2013 to January 1, 2016, 32,985 common shares will be issued upon the vesting of these performance units on March 1, 2016. For the performance units granted in 2012, based on DFT’s total stockholder return compared to the MSCI US REIT index return for the period from January 1, 2012 to January 1, 2015, no common shares were issued.

13. Earnings Per Share of the R

13. Earnings Per Share of the REIT	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Earnings Per Share [Text Block]	(Loss) Earnings Per Share of DFT The following table sets forth the reconciliation of basic and diluted average shares outstanding used in the computation of earnings per share of common stock (in thousands except for share and per share amounts): Twelve months ended December 31, 2015 2014 2013 Basic and Diluted Shares Outstanding Weighted average common shares – basic 65,184,013 65,486,108 64,645,316 Effect of dilutive securities — 600,271 828,723 Weighted average common shares – diluted 65,184,013 66,086,379 65,474,039 Calculation of Earnings per Share – Basic Net (loss) income attributable to common shares $ (25,338 ) $ 78,662 $ 21,146 Net income allocated to unvested restricted shares (599 ) (484 ) (267 ) Net (loss) income attributable to common shares, adjusted (25,937 ) 78,178 20,879 Weighted average common shares – basic 65,184,013 65,486,108 64,645,316 (Loss) earnings per common share – basic $ (0.40 ) $ 1.19 $ 0.32 Calculation of Earnings per Share – Diluted Net (loss) income attributable to common shares $ (25,937 ) $ 78,178 $ 21,146 Adjustments to redeemable noncontrolling interests — — 55 Adjusted net (loss) income available to common shares (25,937 ) 78,178 21,201 Weighted average common shares – diluted 65,184,013 66,086,379 65,474,039 (Loss) earnings per common share – diluted $ (0.40 ) $ 1.18 $ 0.32 The following table sets forth the amount of stock options and performance units that have been excluded from the calculation of diluted earnings per share (in millions): Twelve months ended December 31, 2015 2014 2013 Stock Options 0.6 — 0.6 Performance Units 0.1 0.1 0.1 All of the stock options were antidilutive for the twelve months ended December 31, 2015 because of the net loss incurred during the year. The stock options presented above for the twelve months ended December 31, 2013 were excluded from the calculation of diluted earnings per share as their effect would have been antidilutive. The performance units presented above for the twelve months ended December 31, 2015 , 2014 and 2013 were antidilutive because the vesting conditions for these awards were not met in each of these years.

14. Earnings Per Unit of the Op

14. Earnings Per Unit of the Operating Partnership	12 Months Ended
	Dec. 31, 2015
Earnings Per Unit [Abstract]
Earnings per unit of the Operating Partnership [Text Block]	(Loss) Earnings Per Unit of the Operating Partnership The following table sets forth the reconciliation of basic and diluted average units outstanding used in the computation of earnings per unit: Twelve months ended December 31, 2015 2014 2013 Basic and Diluted Units Outstanding Weighted average common units – basic (includes redeemable partnership units and units of general and limited partners) 80,599,199 81,053,127 80,580,556 Effect of dilutive securities — 600,271 828,723 Weighted average common units – diluted 80,599,199 81,653,398 81,409,279 The following table sets forth the amount of stock options and performance units that have been excluded from the calculation of diluted earnings per unit (in millions): Twelve months ended December 31, 2015 2014 2013 Stock Options 0.6 — 0.6 Performance Units 0.1 0.1 0.1 All of the stock options were antidilutive for the twelve months ended December 31, 2015 because of the net loss incurred during the year. The stock options presented above for the twelve months ended December 31, 2013 were excluded from the calculation of diluted earnings per share as their effect would have been antidilutive. The performance units presented above for the twelve months ended December 31, 2015 , 2014 and 2013 were antidilutive because the vesting conditions for these awards were not met in each of these years.

15. Employee Benefit Plan (Note

15. Employee Benefit Plan (Notes)	12 Months Ended
	Dec. 31, 2015
Compensation and Employee Benefit Plans [Text Block]	Employee Benefit Plan We have a tax qualified retirement plan (“401(k) Plan”) that provides employees with an opportunity to save for retirement on a tax advantaged basis. Employees participate in the 401(k) Plan on their first day of employment and are able to defer compensation up to the limits established by the Internal Revenue Service. We match 50% of the employees' contributions up to a maximum match contribution of 4% of the employees' eligible compensation. Our contributions vest immediately. For the year ended December 31, 2015 , we contributed $0.5 million to the 401(k) Plan, and for each of the years ended December 31, 2014 and 2013 , we contributed $0.4 million to the 401(k) Plan.

16. Fair Value

16. Fair Value	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Disclosures [Text Block]	Fair Value Assets and Liabilities Measured at Fair Value We follow the authoritative guidance issued by the FASB relating to fair value measurements that defines fair value, establishes a framework for measuring fair value, and expands disclosures about fair value measurements. The guidance applies to reported balances that are required or permitted to be measured at fair value under existing accounting pronouncements; accordingly, the guidance does not require any new fair value measurements of reported balances. The guidance excludes the accounting for leases, as well as other authoritative guidance that address fair value measurements on lease classification and measurement. The authoritative guidance issued by the FASB emphasizes that fair value is a market-based measurement, not an entity-specific measurement. Therefore, a fair value measurement should be determined based on the assumptions that market participants would use in pricing the asset or liability. Level 1 inputs utilize quoted prices (unadjusted) in active markets for identical assets or liabilities that we have the ability to access. Level 2 inputs are inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. Level 2 inputs may include quoted prices for similar assets and liabilities in active markets, as well as inputs that are observable for the asset or liability (other than quoted prices), such as interest rates, foreign exchange rates, and yield curves that are observable at commonly quoted intervals. Level 3 inputs are unobservable inputs for the asset or liability, which are typically based on an entity's own assumptions, as there is little, if any, related market activity. In instances where the determination of the fair value measurement is based on inputs from different levels of the fair value hierarchy, the level in the fair value hierarchy within which the entire fair value measurement falls is based on the lowest level input that is significant to the fair value measurement in its entirety. Our assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the asset or liability. The authoritative guidance issued by the FASB requires disclosure of the fair value of financial instruments. Fair value estimates are subjective in nature and are dependent on a number of important assumptions, including estimates of future cash flows, risks, discount rates, and relevant comparable market information associated with each financial instrument. The use of different market assumptions and estimation methodologies may have a material effect on the reported estimated fair value amounts. Accordingly, the amounts are not necessarily indicative of the amounts we would realize in a current market exchange. The following methods and assumptions were used in estimating the fair value amounts and disclosures for financial instruments as of December 31, 2015 and 2014 : • Cash and cash equivalents: The carrying amount of cash and cash equivalents reported in the accompanying consolidated balance sheets approximates fair value because of the short maturity of these instruments (i.e., less than 90 days). • Rents and other receivables, accounts payable and accrued liabilities, and prepaid rents: The carrying amount of these assets and liabilities reported in the accompanying consolidated balance sheets approximates fair value because of the short-term nature of these amounts. • Debt: As of December 31, 2015 , the combined balance of our Unsecured Notes due 2021, Unsecured Notes due 2023, Unsecured Term Loan and ACC3 Term Loan, excluding the effect of deferred financing costs, was $1,213.1 million with a fair value of $1,237.2 million . The Unsecured Notes due 2021 and Unsecured Notes due 2023 were valued based on Level 2 data which consisted of a quoted price from Bloomberg. The ACC3 Loan and the Unsecured Term Loan were valued based on Level 3 data which consisted of a one-month LIBOR swap rate coterminous with the maturity of each loan plus a spread consistent with current market conditions. As of December 31, 2014 , the combined balance of our Unsecured Notes due 2021, Unsecured Term Loan, Unsecured Credit Facility and ACC3 Term Loan, excluding the effect of deferred financing costs, was $1,025.0 million with a fair value of $1,037.8 million . The Unsecured Notes due 2021 were valued based on Level 2 data which consisted of a quoted price from Bloomberg. We believe that the carrying values of our ACC3 Term Loan, Unsecured Credit Facility and Unsecured Term Loan approximated each of their fair values as of December 31, 2014 . Each of these loans bears interest at LIBOR plus a spread that is consistent with current market conditions.

17. Quarterly Financial Informa

17. Quarterly Financial Information (Notes)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information [Text Block]	Quarterly Financial Information (unaudited) The table below reflects the selected quarterly information for the years ended December 31, 2015 and 2014 (in thousands except share data): Three months ended December 31, 2015 September 30, 2015 June 30, 2015 March 31, 2015 Total revenue $ 115,923 $ 115,337 $ 113,826 $ 107,314 Net (loss) income (91,953 ) 30,393 31,141 26,333 Net (loss) income attributable to common shares (79,871 ) 19,062 19,668 15,803 Net (loss) income attributable to common shares per common share-basic (1.23 ) 0.29 0.30 0.24 Net (loss) income attributable to common shares per common share-diluted (1.23 ) 0.29 0.30 0.24 Three months ended December 31, 2014 September 30, 2014 June 30, 2014 March 31, 2014 Total revenue $ 107,977 $ 105,578 $ 101,950 $ 102,087 Net income 29,737 30,272 32,958 31,644 Net income attributable to common shares 18,536 18,960 21,121 20,045 Net income attributable to common shares per common share-basic (1) 0.28 0.29 0.32 0.30 Net income attributable to common shares per common share-diluted 0.28 0.29 0.32 0.30 (1) Amounts do not equal full year results due to rounding.

18. Supplemental Consolidating

18. Supplemental Consolidating Financial Data for Subsidiary Guarantors of the Unsecured Notes	12 Months Ended
	Dec. 31, 2015
Supplemental Consolidating Financial Data for Subsidiary Guarantors of the Unsecured Notes [Abstract]
Additional Financial Information Disclosure [Text Block]	Supplemental Consolidating Financial Data for Subsidiary Guarantors of the Unsecured Notes Our Unsecured Notes due 2021 and Unsecured Notes due 2023 are unconditionally guaranteed, jointly and severally on a senior unsecured basis by DFT and certain of our subsidiaries, including the subsidiaries that own the ACC2, ACC4, ACC5, ACC6, VA3, VA4, CH1, NJ1 and SC1 data centers and the SC2 land (collectively, the "Subsidiary Guarantors"), but excluding the subsidiaries that own the ACC3, ACC7 and CH2 data center facilities, the ACC8 and CH3 land and the TRS (collectively, the "Subsidiary Non-Guarantors"). The following consolidating financial information sets forth the financial position as of December 31, 2015 and December 31, 2014 and the results of operations and cash flows for the years ended December 31, 2015 , 2014 and 2013 of the Operating Partnership, Subsidiary Guarantors and the Subsidiary Non-Guarantors. DUPONT FABROS TECHNOLOGY, L.P. SUPPLEMENTAL CONSOLIDATING BALANCE SHEETS (in thousands except share data) December 31, 2015 Operating Partnership Subsidiary Guarantors Subsidiary Non-Guarantors Eliminations Consolidated Total ASSETS Income producing property: Land $ — $ 84,258 $ 9,945 $ — $ 94,203 Buildings and improvements — 2,399,016 337,920 — 2,736,936 — 2,483,274 347,865 — 2,831,139 Less: accumulated depreciation — (522,096 ) (38,741 ) — (560,837 ) Net income producing property — 1,961,178 309,124 — 2,270,302 Construction in progress and land held for development — 25,545 275,394 — 300,939 Net real estate — 1,986,723 584,518 — 2,571,241 Cash and cash equivalents 21,697 — 5,318 — 27,015 Rents and other receivables 1,391 7,563 634 — 9,588 Deferred rent — 122,830 6,111 — 128,941 Lease contracts above market value, net — 6,029 — — 6,029 Deferred costs, net 3,236 14,250 6,288 — 23,774 Investment in affiliates 2,546,465 — — (2,546,465 ) — Prepaid expenses and other assets 3,025 39,642 2,022 — 44,689 Total assets $ 2,575,814 $ 2,177,037 $ 604,891 $ (2,546,465 ) $ 2,811,277 LIABILITIES AND PARTNERS’ CAPITAL Liabilities: Line of credit $ — $ — $ — $ — $ — Mortgage notes payable, net of deferred financing costs — — 114,075 — 114,075 Unsecured term loan, net of deferred financing costs 249,172 — — — 249,172 Unsecured notes payable, net of discount and deferred financing costs 834,963 — — — 834,963 Accounts payable and accrued liabilities 4,516 23,615 4,170 — 32,301 Construction costs payable 43 293 21,707 — 22,043 Accrued interest payable 11,815 — 6 — 11,821 Distribution payable 43,906 — — — 43,906 Lease contracts below market value, net — 4,132 — — 4,132 Prepaid rents and other liabilities 12 62,630 4,835 — 67,477 Total liabilities 1,144,427 90,670 144,793 — 1,379,890 Redeemable partnership units 479,189 — — — 479,189 Commitments and contingencies — — — — — Limited Partners’ Capital: Series A cumulative redeemable perpetual preferred units, 7,400,000 issued and outstanding at December 31, 2015 185,000 — — — 185,000 Series B cumulative redeemable perpetual preferred units, 6,650,000 issued and outstanding at December 31, 2015 166,250 — — — 166,250 Common units, 65,443,277 issued and outstanding at December 31, 2015 594,927 2,086,367 460,098 (2,546,465 ) 594,927 General partner’s capital, 662,373 common units issued and outstanding at December 31, 2015 6,021 — — — 6,021 Total partners’ capital 952,198 2,086,367 460,098 (2,546,465 ) 952,198 Total liabilities & partners’ capital $ 2,575,814 $ 2,177,037 $ 604,891 $ (2,546,465 ) $ 2,811,277 DUPONT FABROS TECHNOLOGY, L.P. SUPPLEMENTAL CONSOLIDATING BALANCE SHEETS (in thousands except share data) December 31, 2014 Operating Partnership Subsidiary Guarantors Subsidiary Non-Guarantors Eliminations Consolidated Total ASSETS Income producing property: Land $ — $ 79,935 $ 3,858 $ — $ 83,793 Buildings and improvements — 2,427,706 195,833 — 2,623,539 — 2,507,641 199,691 — 2,707,332 Less: accumulated depreciation — (473,203 ) (31,666 ) — (504,869 ) Net income producing property — 2,034,438 168,025 — 2,202,463 Construction in progress and land held for development — 145,229 213,736 — 358,965 Net real estate — 2,179,667 381,761 — 2,561,428 Cash and cash equivalents 21,806 — 3,574 — 25,380 Rents and other receivables 1,775 5,513 825 — 8,113 Deferred rent — 139,542 2,823 — 142,365 Lease contracts above market value, net — 8,054 — — 8,054 Deferred costs, net 3,669 16,098 5,107 — 24,874 Investment in affiliates 2,547,049 — — (2,547,049 ) — Prepaid expenses and other assets 2,865 43,866 1,564 — 48,295 Total assets $ 2,577,164 $ 2,392,740 $ 395,654 $ (2,547,049 ) $ 2,818,509 LIABILITIES AND PARTNERS’ CAPITAL Liabilities: Line of credit $ 60,000 $ — $ — $ — $ 60,000 Mortgage notes payable, net of deferred financing costs — — 113,667 — 113,667 Unsecured term loan, net of deferred financing costs 248,945 — — — 248,945 Unsecured notes payable, net of discount and deferred financing costs 588,767 — — — 588,767 Accounts payable and accrued liabilities 4,432 19,580 2,961 — 26,973 Construction costs payable — 4,312 28,637 — 32,949 Accrued interest payable 10,754 — 5 — 10,759 Distribution payable 39,981 — — — 39,981 Lease contracts below market value, net — 7,037 — — 7,037 Prepaid rents and other liabilities 28 61,728 3,418 — 65,174 Total liabilities 952,907 92,657 148,688 — 1,194,252 Redeemable partnership units 513,134 — — — 513,134 Commitments and contingencies — — — — — Limited Partners’ Capital: Series A cumulative redeemable perpetual preferred units, 7,400,000 issued and outstanding at December 31, 2014 185,000 — — — 185,000 Series B cumulative redeemable perpetual preferred units, 6,650,000 issued and outstanding at December 31, 2014 166,250 — — — 166,250 Common units, 65,399,431 issued and outstanding at December 31, 2014 752,254 2,300,083 246,966 (2,547,049 ) 752,254 General partner’s capital, 662,373 common units issued and outstanding at December 31, 2014 7,619 — — — 7,619 Total partners’ capital 1,111,123 2,300,083 246,966 (2,547,049 ) 1,111,123 Total liabilities & partners’ capital $ 2,577,164 $ 2,392,740 $ 395,654 $ (2,547,049 ) $ 2,818,509 Year ended December 31, 2015 Operating Partnership Subsidiary Guarantors Subsidiary Non-Guarantors Eliminations Consolidated Total Revenues: Base rent $ 18,061 $ 268,433 $ 30,302 $ (18,211 ) $ 298,585 Recoveries from tenants — 127,877 11,660 — 139,537 Other revenues — 1,787 12,621 (130 ) 14,278 Total revenues 18,061 398,097 54,583 (18,341 ) 452,400 Expenses: Property operating costs — 131,644 16,598 (18,191 ) 130,051 Real estate taxes and insurance — 19,942 1,393 — 21,335 Depreciation and amortization 43 94,371 9,630 — 104,044 General and administrative 17,574 57 433 — 18,064 Impairment on investment in real estate — 119,267 3,205 — 122,472 Other expenses 6,151 133 10,725 (150 ) 16,859 Total expenses 23,768 365,414 41,984 (18,341 ) 412,825 Operating (loss) income (5,707 ) 32,683 12,599 — 39,575 Interest income 60 — — — 60 Interest: Expense incurred (50,081 ) 1,327 8,184 — (40,570 ) Amortization of deferred financing costs (3,454 ) 107 196 — (3,151 ) Equity in earnings 55,096 — — (55,096 ) — Net (loss) income (4,086 ) 34,117 20,979 (55,096 ) (4,086 ) Preferred unit distributions (27,245 ) — — — (27,245 ) Net (loss) income attributable to common units $ (31,331 ) $ 34,117 $ 20,979 $ (55,096 ) $ (31,331 ) Year ended December 31, 2014 Operating Partnership Subsidiary Guarantors Subsidiary Non-Guarantors Eliminations Consolidated Total Revenues: Base rent $ 17,499 $ 267,454 $ 18,413 $ (17,650 ) $ 285,716 Recoveries from tenants — 115,185 9,668 — 124,853 Other revenues — 1,657 5,489 (123 ) 7,023 Total revenues 17,499 384,296 33,570 (17,773 ) 417,592 Expenses: Property operating costs — 123,140 11,822 (17,623 ) 117,339 Real estate taxes and insurance — 13,323 872 — 14,195 Depreciation and amortization 63 90,770 5,947 — 96,780 General and administrative 16,159 82 940 — 17,181 Other expenses 3,508 1,526 4,338 (150 ) 9,222 Total expenses 19,730 228,841 23,919 (17,773 ) 254,717 Operating (loss) income (2,231 ) 155,455 9,651 — 162,875 Interest income 115 — 1 — 116 Interest: Expense incurred (41,222 ) 4,323 3,200 — (33,699 ) Amortization of deferred financing costs (3,173 ) 273 (80 ) — (2,980 ) Loss on early extinguishment of debt (1,701 ) — — — (1,701 ) Equity in earnings 172,823 — — (172,823 ) — Net income (loss) 124,611 160,051 12,772 (172,823 ) 124,611 Preferred unit distributions (27,245 ) — — — (27,245 ) Net income attributable to common units $ 97,366 $ 160,051 $ 12,772 $ (172,823 ) $ 97,366 Year ended December 31, 2013 Operating Partnership Subsidiary Guarantors Subsidiary Non-Guarantors Eliminations Consolidated Total Revenues: Base rent $ 15,301 $ 248,719 $ 17,126 $ (15,451 ) $ 265,695 Recoveries from tenants — 94,794 9,477 — 104,271 Other revenues — 1,668 3,613 (138 ) 5,143 Total revenues 15,301 345,181 30,216 (15,589 ) 375,109 Expenses: Property operating costs 198 108,536 10,227 (15,439 ) 103,522 Real estate taxes and insurance — 13,931 449 — 14,380 Depreciation and amortization 81 88,556 4,421 — 93,058 General and administrative 15,605 97 559 — 16,261 Other expenses 778 304 2,718 (150 ) 3,650 Total expenses 16,662 211,424 18,374 (15,589 ) 230,871 Operating (loss) income (1,361 ) 133,757 11,842 — 144,238 Interest income (148 ) 20 — 265 137 Interest: Expense incurred (47,343 ) 351 814 (265 ) (46,443 ) Amortization of deferred financing costs (3,054 ) (167 ) (128 ) — (3,349 ) Loss on early extinguishment of debt (39,278 ) (1,700 ) — — (40,978 ) Equity in earnings 144,789 — — (144,789 ) — Net income (loss) 53,605 132,261 12,528 (144,789 ) 53,605 Preferred unit distributions (27,245 ) — — — (27,245 ) Net income attributable to common units $ 26,360 $ 132,261 $ 12,528 $ (144,789 ) $ 26,360 DUPONT FABROS TECHNOLOGY, L.P. SUPPLEMENTAL CONSOLIDATING STATEMENTS OF CASH FLOWS (in thousands) Year ended December 31, 2015 Operating Partnership Subsidiary Guarantors Subsidiary Non-Guarantors Eliminations Consolidated Total Cash flow from operating activities Net cash (used in) provided by operating activities $ (55,999 ) $ 278,557 $ 32,466 $ — $ 255,024 Cash flow from investing activities Investments in real estate – development (415 ) (8,996 ) (207,928 ) — (217,339 ) Land acquisition costs — — (8,600 ) — (8,600 ) Investments in affiliates 68,074 (264,211 ) 196,137 — — Interest capitalized for real estate under development (27 ) (1,327 ) (10,210 ) — (11,564 ) Improvements to real estate — (3,401 ) (58 ) — (3,459 ) Additions to non-real estate property (93 ) (622 ) (38 ) — (753 ) Net cash provided by (used in) investing activities 67,539 (278,557 ) (30,697 ) — (241,715 ) Cash flow from financing activities Line of credit: Proceeds 120,000 — — — 120,000 Repayments (180,000 ) — — — (180,000 ) Unsecured notes payable: Proceeds 248,012 — — — 248,012 Payments of financing costs (4,715 ) — (25 ) — (4,740 ) Equity compensation (payments) proceeds 249 — — — 249 OP unit repurchases (31,912 ) — — — (31,912 ) Distributions (163,283 ) — — — (163,283 ) Net cash (used in) provided by financing activities (11,649 ) — (25 ) — (11,674 ) Net (decrease) increase in cash and cash equivalents (109 ) — 1,744 — 1,635 Cash and cash equivalents, beginning 21,806 — 3,574 — 25,380 Cash and cash equivalents, ending $ 21,697 $ — $ 5,318 $ — $ 27,015 DUPONT FABROS TECHNOLOGY, L.P. SUPPLEMENTAL CONSOLIDATING STATEMENTS OF CASH FLOWS (in thousands) Year ended December 31, 2014 Operating Partnership Subsidiary Guarantors Subsidiary Non-Guarantors Eliminations Consolidated Total Cash flow from operating activities Net cash (used in) provided by operating activities $ (40,234 ) $ 264,409 $ 20,339 $ — $ 244,514 Cash flow from investing activities Investments in real estate – development (404 ) (111,791 ) (153,179 ) — (265,374 ) Investments in affiliates 5,654 (146,188 ) 140,534 — — Interest capitalized for real estate under development (10 ) (4,323 ) (5,311 ) — (9,644 ) Improvements to real estate — (1,850 ) (66 ) — (1,916 ) Additions to non-real estate property (20 ) (257 ) (39 ) — (316 ) Net cash provided by (used in) investing activities 5,220 (264,409 ) (18,061 ) — (277,250 ) Cash flow from financing activities Line of credit: Proceeds 60,000 — — — 60,000 Unsecured term loan: Proceeds 96,000 — — — 96,000 Payments of financing costs (3,514 ) — (315 ) — (3,829 ) Equity compensation proceeds 4,363 — — — 4,363 Distributions (132,932 ) — — — (132,932 ) Net cash provided by (used in) financing activities 23,917 — (315 ) — 23,602 Net (decrease) increase in cash and cash equivalents (11,097 ) — 1,963 — (9,134 ) Cash and cash equivalents, beginning 32,903 — 1,611 — 34,514 Cash and cash equivalents, ending $ 21,806 $ — $ 3,574 $ — $ 25,380 Year ended December 31, 2013 Operating Partnership Subsidiary Guarantors Subsidiary Non-Guarantors Eliminations Consolidated Total Cash flow from operating activities Net cash (used in) provided by operating activities $ (48,725 ) $ 225,903 $ 16,583 $ — $ 193,761 Cash flow from investing activities Investments in real estate – development (9 ) (50,827 ) (78,496 ) — (129,332 ) Land Acquisition Costs — — (14,186 ) — (14,186 ) Investments in affiliates 62,508 (28,856 ) (33,652 ) — — Interest capitalized for real estate under development — (1,399 ) (2,375 ) — (3,774 ) Improvements to real estate — (5,513 ) (244 ) — (5,757 ) Additions to non-real estate property (6 ) (65 ) — — (71 ) Net cash provided by (used) in investing activities 62,493 (86,660 ) (128,953 ) — (153,120 ) Cash flow from financing activities Line of credit: Proceeds 102,000 — — — 102,000 Repayments (120,000 ) — — — (120,000 ) Mortgage notes payable: Proceeds — — 115,000 — 115,000 Lump sum payoffs — (138,300 ) — — (138,300 ) Repayments — (1,300 ) — — (1,300 ) Unsecured term loan: Proceeds 154,000 — — — 154,000 Unsecured notes payable: Proceeds 600,000 — — — 600,000 Repayments (550,000 ) — — — (550,000 ) Payments of financing costs (16,419 ) (4 ) (1,700 ) — (18,123 ) Payments for early extinguishment of debt (32,544 ) — — — (32,544 ) Equity compensation proceeds 1,711 — — — 1,711 Stock repurchases (37,792 ) — — — (37,792 ) Distributions (100,061 ) — — — (100,061 ) Net cash provided by (used in) financing activities 895 (139,604 ) 113,300 — (25,409 ) Net increase (decrease) in cash and cash equivalents 14,663 (361 ) 930 — 15,232 Cash and cash equivalents, beginning 18,240 361 681 — 19,282 Cash and cash equivalents, ending $ 32,903 $ — $ 1,611 $ — $ 34,514

Schedule II - Consolidated Allo

Schedule II - Consolidated Allowance for Doubtful Accounts (Notes)	12 Months Ended
	Dec. 31, 2015
Valuation and Qualifying Accounts Disclosure [Line Items]
Schedule of Valuation and Qualifying Accounts Disclosure [Text Block]	Balance at Beginning of Period Charges to Operations Net Recovery (Deductions) Balance at End of Period Allowance for doubtful accounts: Twelve months ended December 31, 2015 $ 8,520 $ 372 $ (3,651 ) $ 5,241 Twelve months ended December 31, 2014 3,700 4,829 (9 ) 8,520 Twelve months ended December 31, 2013 2,961 739 — 3,700

Schedule III - Consolidated Rea

Schedule III - Consolidated Real Estate and Accumulated Depreciation (Notes)	12 Months Ended
	Dec. 31, 2015
Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule III, Real Estate and Accumulated Depreciation Disclosure [Text Block]	Encum-brances Initial Cost at Acquisition / Placement into Service Costs Capitalized Gross Carry Amount at Accumulated Year Year Land Building and improvements / Construction in progress Land Buildings & Land Building and improvements / Construction in progress Total Operating Properties ACC2 (1) $ — $ 2,500 $ 157,100 $ — $ (2,908 ) $ 2,500 $ 154,192 $ 156,692 $ (50,969 ) 2005 2001 ACC3 (2) 115,000 1,071 92,631 — 3,346 1,071 95,977 97,048 (32,723 ) 2006 2001 ACC4 (1) — 6,600 535,526 — 3,126 6,600 538,652 545,252 (157,174 ) 2007 2006 ACC5 (1) — 6,443 292,369 — 6,399 6,443 298,768 305,211 (60,744 ) 2009-2010 2007 ACC6 (1) — 5,518 215,235 — 1,462 5,518 216,697 222,215 (27,699 ) 2011-2013 2007 ACC7 Phase I and II — 4,876 167,766 — — 4,876 167,766 172,642 (4,806 ) 2014-2015 2011 CH1 (1) — 23,611 357,194 — 1,545 23,611 358,739 382,350 (70,407 ) 2008-2012 2007 CH2 Phase I — 3,998 71,778 — 69 3,998 71,847 75,845 (1,212 ) 2015 2013 NJ1 Phase I (1) (3) — 4,311 190,970 (727 ) (117,749 ) 3,584 73,221 76,805 — 2010 2007 SC1 (1) — 20,202 429,572 — 2,985 20,202 432,557 452,759 (39,013 ) 2011-2015 2007 VA3 (1) — 9,000 172,881 — 6,140 9,000 179,021 188,021 (65,458 ) 2003 2003 VA4 (1) — 6,800 140,575 — 8,924 6,800 149,499 156,299 (50,632 ) 2005 2005 Subtotal 115,000 94,930 2,823,597 (727 ) (86,661 ) 94,203 2,736,936 2,831,139 (560,837 ) Development Properties ACC7 Phases III and IV — 4,876 115,739 — — 4,876 115,739 120,615 — 2011 CH2 Phases II and III — 10,395 131,821 — — 10,395 131,821 142,216 — 2013 NJ1 Phase II (1) — 3,584 14,689 — — 3,584 14,689 18,273 — 2007 ACC8 — 3,785 458 — — 3,785 458 4,243 — 2007 CH3 — 8,305 15 — — 8,305 15 8,320 — 2015 SC2 (1) — 5,232 2,040 — — 5,232 2,040 7,272 — 2007 Subtotal — 36,177 264,762 — — 36,177 264,762 300,939 — Grand Total (4) $ 115,000 $ 131,107 $ 3,088,359 $ (727 ) $ (86,661 ) $ 130,380 $ 3,001,698 $ 3,132,078 $ (560,837 ) (1) The subsidiaries that own these data centers and development properties are guarantors of our Unsecured Notes due 2021 and 2023, our Unsecured Credit Facility and our Unsecured Term Loan. (2) The subsidiary that owns this data center is encumbered by our ACC3 Term Loan. (3) The carrying amount of our NJ1 data center was reduced as a result of an impairment charge that was recorded during the fourth quarter of 2015. This adjustment is reflected as a reduction to costs capitalized subsequent to acquisition / placement into service. (4) The aggregate gross cost of our properties for federal income tax purposes was $2.59 billion (unaudited) as of December 31, 2015 . 2015 2014 2013 Real estate assets Balance, beginning of period $ 3,066,297 $ 2,799,010 $ 2,607,630 Additions - property acquisitions 8,600 — 14,186 Additions - improvements 221,588 267,357 177,194 Deductions - write-offs, impairments (164,407 ) (70 ) — Balance, end of period $ 3,132,078 $ 3,066,297 $ 2,799,010 Accumulated depreciation Balance, beginning of period $ 504,869 $ 413,394 $ 325,740 Additions - depreciation 97,988 91,545 87,654 Deductions - write-offs (42,020 ) (70 ) — Balance, end of period $ 560,837 $ 504,869 $ 413,394

2. Significant Accounting Pol28

2. Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Basis of Presentation [Text Block]	Basis of Presentation This report combines the annual reports on Form 10-K for the year ended December 31, 2015 of DuPont Fabros Technology, Inc. and DuPont Fabros Technology, L.P. References to “DFT” mean DuPont Fabros Technology, Inc. and its controlled subsidiaries; and references to the “Operating Partnership” or “OP” mean DuPont Fabros Technology, L.P. and its controlled subsidiaries. We believe combining the annual reports on Form 10-K of DFT and the Operating Partnership into this single report provides the following benefits: • enhances investors’ understanding of DFT and the Operating Partnership by enabling investors to view the business as a whole in the same manner as management views and operates the business; • eliminates duplicative disclosure and provides a more streamlined and readable presentation since a substantial portion of the disclosure in this report applies to both DFT and the Operating Partnership; and • creates time and cost efficiencies through the preparation of one combined report instead of two separate reports. We operate DFT and the Operating Partnership as one business. The management of DFT consists of the same employees as the management of the Operating Partnership. We believe it is important for investors to understand the few differences between DFT and the Operating Partnership in the context of how DFT and the Operating Partnership operate as a consolidated company. DFT is a REIT, whose only material asset is its ownership of OP units of the Operating Partnership. As a result, DFT does not conduct business itself, other than acting as the sole general partner of the Operating Partnership, issuing public equity from time to time and guaranteeing unsecured debt of the Operating Partnership. DFT has not issued any indebtedness, but has guaranteed all of the unsecured debt of the Operating Partnership. The Operating Partnership, through its wholly-owned subsidiaries, holds all the real estate assets of the Company. Except for net proceeds from public equity issuances by DFT, which are contributed to the Operating Partnership in exchange for OP units or preferred units, the Operating Partnership generates all remaining capital required by our business. These sources include the Operating Partnership’s operations, its direct or indirect incurrence of indebtedness, and the issuance of partnership units. As general partner with control of the Operating Partnership, DFT consolidates the Operating Partnership for financial reporting purposes. The presentation of stockholders’ equity and partners’ capital are the main areas of difference between the consolidated financial statements of DFT and those of the Operating Partnership. The Operating Partnership’s capital includes preferred units and general and limited common units that are owned by DFT and the other partners. DFT’s stockholders’ equity includes preferred stock, common stock, additional paid in capital and retained earnings. The common limited partnership interests held by the limited partners (other than DFT) in the Operating Partnership are presented as “redeemable partnership units” in the Operating Partnership’s consolidated financial statements and as “redeemable noncontrolling interests-operating partnership” in DFT’s consolidated financial statements. The only difference between the assets and liabilities of DFT and the Operating Partnership as of December 31, 2015 is a $4.2 million bank account held by DFT that is not part of the Operating Partnership. Net income is the same for DFT and the Operating Partnership. The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles, or GAAP. All significant intercompany accounts and transactions have been eliminated in the consolidated financial statements. We have one reportable segment consisting of investments in data centers located in the United States. All of our properties generate similar types of revenues and expenses related to customer rent and reimbursements and operating expenses. The delivery of our products is consistent across all properties and although services are provided to a range of customers, the types of services provided to them are limited to a few core principles. As such, the properties in our portfolio have similar economic characteristics and the nature of the products and services provided to our customers and the method to distribute such services are consistent throughout the portfolio.
Use of Estimates [Policy Text Block]	Use of Estimates The preparation of financial statements in conformity with GAAP requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosures of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates.
Property [Policy Text Block]	Property All capital improvements for the income-producing properties that extend their useful life are capitalized to individual building components, including interest and real estate taxes incurred during the period of development, and depreciated over their estimated useful lives. Interest is capitalized during the period of development based upon applying the property’s specific borrowing rate to the actual development costs expended up to specific borrowings, if any, and then applying our weighted-average borrowing rate to any residual development costs expended during the construction period. Interest is capitalized until the property has reached substantial completion and is ready for its intended use. Interest costs capitalized totaled $12.3 million , $10.2 million and $4.0 million for the years ended December 31, 2015 , 2014 and 2013 , respectively. We cease interest capitalization when a development is temporarily suspended or placed in service. We capitalize pre-development costs, including internal costs, incurred in pursuit of new development opportunities for which we believe future development is probable. Future development is dependent upon various factors, including zoning and regulatory approval, rental market conditions, construction costs and availability of capital. Pre-development costs incurred for which future development is not yet considered probable are expensed as incurred. In addition, if the status of such a pre-development opportunity changes, making future development no longer probable, any capitalized pre-development costs are written-off with a charge to expense. Furthermore, the revenue from incidental operations received from the current improvements in excess of any incremental costs are recorded as a reduction of total capitalized costs of the development project and not as a part of net income. The capitalization of costs during the development of assets (including interest and related loan fees, property taxes and other direct and indirect costs) begins when development efforts commence and ends when the asset, or a portion of the asset, is substantially complete and ready for its intended use. For the years ended December 31, 2015 , 2014 and 2013 , we capitalized $7.5 million , $4.5 million and $3.3 million , respectively, of internal development and leasing costs on all of our data centers. The fair value of in-place leases consists of the following components, as applicable: (1) the estimated cost to replace the leases, including foregone rents during the period of finding a new customer, foregone recovery of customer pass-through, customer improvements, and other direct costs associated with obtaining a new customer (referred to as tenant origination costs); (2) the estimated leasing commissions associated with obtaining a new customer (referred to as leasing commissions); and (3) the above/below market cash flow of the leases, determined by comparing the projected cash flows of the leases in place to projected cash flows of comparable market-rate leases (referred to as lease intangibles). Tenant origination costs are included in buildings and improvements in our accompanying consolidated balance sheets and are amortized as depreciation expense on a straight-line basis over the average remaining life of the underlying leases. Leasing commissions are classified as deferred costs and are amortized as amortization expense on a straight-line basis over the remaining life of the underlying leases. Lease intangible assets and liabilities are classified as lease contracts above and below market value, respectively, and amortized on a straight-line basis as decreases and increases, respectively, to rental revenue over the remaining life of the underlying leases. Should a customer terminate its lease early, the unamortized portions of leasing commissions and lease intangibles associated with that lease are written off to amortization expense or rental revenue, respectively, as further described below. Depreciation on buildings is generally provided on a straight-line basis over 40 years from the date the buildings were placed in service. Building components are depreciated over the life of the respective improvement ranging from 10 to 40 years from the date the components were placed in service. Personal property is depreciated over three years to seven years . Depreciation expense was $98.8 million , $92.3 million and $88.6 million for the years ended December 31, 2015 , 2014 and 2013 , respectively. Included in these amounts is amortization expense related to tenant origination costs, which was $2.0 million for the year ended December 31, 2015 , and $3.1 million for each of the years ended December 31, 2014 and 2013 . Repairs and maintenance costs are expensed as incurred. We review each of our properties for indicators of impairment. Examples of such indicators may include a significant decrease in the market price of the property, a significant adverse change in the extent or manner in which the property is being used in its physical condition, a significant adverse change in legal factors or in the business climate that could affect the value of a property, including an adverse action or assessment by a regulator, an accumulation of costs significantly in excess of the amount originally expected for the development of a property, a history of operating or cash flow losses of the property or a current expectation that, more likely than not, a property will be sold or otherwise disposed of significantly before the end of its previously estimated useful life. When such impairment indicators exist, we review an estimate of the future undiscounted net cash flows expected to result from the real estate investment’s use and eventual disposition and compare that estimate to the carrying value of the property. We assess the recoverability of the carrying value of our assets on a property-by-property basis. We consider factors such as future operating income, trends and prospects, as well as the effects of leasing demand, competition, potential sales proceeds and other factors. If our undiscounted cash flow evaluation indicates that we are unable to recover the carrying value of a real estate investment, an impairment loss is recorded to the extent that the carrying value exceeds the estimated fair value of the property. In the fourth quarter of 2015, we identified our NJ1 data center as an asset that fell outside of our strategic focus on wholesale data center development and operations in our targeted markets, and it became evident that we would, more likely than not, sell NJ1 prior to its previously estimated useful life. In connection with that determination, we evaluated the recoverability of the carrying value for NJ1 and determined that its carrying value was no longer recoverable due to reducing its expected holding period. As a result, for the year ended December 31, 2015, we reduced the carrying value of NJ1 to its estimated fair value by recording an impairment charge of $122.5 million . Estimated fair value was determined using a third party appraisal for NJ1 in conjunction with the guidance in ASC 820, which involved the use of Level 3 inputs. The appraisal was based on the income capitalization approach which derives value using the property's potential income and an average market capitalization rate for comparable sales in the market. There were no impairment losses for the years ended December 31, 2014 and 2013. We classify a data center property as held-for-sale when it meets the necessary criteria, which include when we commit to and actively embark on a plan to sell the asset, the sale is expected to be completed within one year under terms usual and customary for such sales, and actions required to complete the plan indicate that it is unlikely that significant changes to the plan will be made or that the plan will be withdrawn. Data center properties held-for-sale are carried at the lower of cost or fair value less costs to sell. Because we have never sold a data center facility since becoming a public company in 2007 and therefore have no history of selling data center assets, we are not reasonably assured that the sale of NJ1 will occur within one year. Accordingly, as of December 31, 2015 , we did not classify our NJ1 data center, nor any of our other data centers, as held-for-sale.
Cash and Cash Equivalents, Policy [Policy Text Block]	Cash and Cash Equivalents We consider all demand deposits and money market accounts purchased with a maturity date of three months or less, at the date of purchase, to be cash equivalents. Our account balances at one or more institutions exceed the Federal Deposit Insurance Corporation (“FDIC”) insurance coverage and, as a result, there is a concentration of credit risk related to amounts on deposit in excess of FDIC insurance coverage. We have not experienced any losses and believe that the risk is not significant.
Deferred Costs [Policy Text Block]	Deferred Costs Deferred costs, net in our accompanying consolidated balance sheets include both financing and leasing costs. Deferred financing costs represent fees and other costs incurred in obtaining our unsecured line of credit. As of December 31, 2015 , we have early-adopted Accounting Standards Update ("ASU") 2015-03, Interest—Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs , which changed the presentation of deferred financing costs in our accompanying consolidated balance sheets. The new guidance requires that deferred financing costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the debt liability rather than as an asset. However, the FASB subsequently issued ASU 2015-15, Interest—Imputation of Interest (Subtopic 835-30): Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of-Credit Arrangements , which allows an entity to continue to present line of credit issuance costs as an asset, regardless of whether there are any outstanding borrowings on the line of credit. Accordingly, for each of our recognized debt liabilities other than our unsecured revolving credit facility ("Unsecured Credit Facility"), we have reduced these balances by their respective deferred financing cost balances, net of accumulated amortization, and have applied this change retrospectively to all periods presented. Balances of financing costs for our Unsecured Credit Facility, net of accumulated amortization, which are presented within deferred costs, net in our accompanying consolidated balance sheets at December 31, 2015 and 2014 , are as follows (in thousands): December 31, Financing costs presented within deferred costs, net 2015 2014 Financing costs $ 8,198 $ 7,448 Accumulated amortization (4,969 ) (3,779 ) Financing costs, net $ 3,229 $ 3,669 Balances of financing costs for our other recognized debt liabilities, net of accumulated amortization, which are presented as a reduction of each of the respective recognized debt liabilities in our accompanying consolidated balance sheets at December 31, 2015 and 2014 , are as follows (in thousands): December 31, Financing costs presented as a reduction of debt liability balances 2015 2014 Financing costs $ 20,531 $ 16,662 Accumulated amortization (5,618 ) (3,041 ) Financing costs, net $ 14,913 $ 13,621 Financing costs are amortized using the effective-interest rate method or a method that approximates the effective-interest method, over the term of the loan and are included in amortization of deferred financing costs in our consolidated statements of operations. In May 2014, we amended our Unsecured Credit Facility, which, due to the change in composition of lenders comprising the Unsecured Credit Facility's bank group, resulted in the partial write-off of unamortized deferred financing costs totaling $0.3 million . In July 2014, we amended our unsecured term loan agreement ("Unsecured Term Loan"), which, due to the change in composition of lenders comprising the Unsecured Term Loan's bank group, resulted in a loss on early extinguishment of debt of $1.4 million , which included a partial write-off of unamortized deferred financing costs of $0.7 million . In March 2013, we paid off the $138.3 million balance of a term loan which resulted in a write-off of $1.7 million of unamortized deferred financing costs. In September and October 2013, we paid off our senior unsecured notes due 2017 (the "Unsecured Notes due 2017"), which resulted in a write off of $6.7 million of unamortized deferred financing costs. Leasing costs, which include external fees and costs incurred in the successful negotiations of leases, internal costs expended in the successful negotiations of leases or the estimated leasing commissions resulting from the allocation of the purchase price of ACC2, VA3, VA4 and ACC4, are deferred and amortized over the terms of the related leases on a straight-line basis. If an applicable lease terminates prior to the expiration of its initial term, the carrying amount of the costs are written off to amortization expense. In June 2015, we wrote off $0.7 million of unamortized leasing costs to amortization expense related to a former customer in bankruptcy whose leases with us were rejected effective July 1, 2015 pursuant to an order made by the bankruptcy court, described below. Leasing costs incurred for the years ended December 31, 2015 , 2014 and 2013 are as follows (in millions): Year ended December 31, 2015 2014 2013 Costs incurred for new leases $ 2.1 $ 2.0 $ 0.9 Costs incurred for renewals 1.2 0.2 1.2 Costs incurred for re-leases 0.9 2.0 — Total leasing costs incurred $ 4.2 $ 4.2 $ 2.1 Amortization of deferred leasing costs totaled $4.9 million , $4.1 million and $4.1 million for the years ended December 31, 2015 , 2014 and 2013 , respectively. Balances, net of accumulated amortization, at December 31, 2015 and 2014 are as follows (in thousands): December 31, 2015 2014 Leasing costs $ 50,503 $ 52,358 Accumulated amortization (29,958 ) (31,153 ) Leasing costs, net $ 20,545 $ 21,205
Inventory [Policy Text Block]	Inventory We maintain fuel inventory for our generators, which is recorded at the lower of cost (on a first-in, first-out basis) or market. As of December 31, 2015 and 2014 , the fuel inventory was $4.5 million and $4.3 million , respectively, and is included in prepaid expenses and other assets in the accompanying consolidated balance sheets.
Prepaid Rents [Policy Text Block]	Prepaid Rents Prepaid rents, typically prepayment of the following month’s rent, consist of payments received from customers prior to the time the payments are earned and are recognized as revenue in subsequent periods when earned.
Rental Income [Policy Text Block]	Rental Income We, as a lessor, have retained substantially all the risks and benefits of ownership and account for our leases as operating leases. For lease agreements that provide for scheduled fixed and determinable rent increases, rental income is recognized on a straight-line basis over the non-cancellable term of the leases, which commences when control of the space and critical power have been provided to the customer. If the lease contains an early termination clause with a penalty payment, we determine the lease termination date by evaluating whether the penalty reasonably assures that the lease will not be terminated early. Straight-line rents receivable are included in deferred rent, net in the accompanying consolidated balance sheets. Lease inducements, which include free rent or cash payments to customers, are amortized as a reduction of rental income over the non-cancellable lease term. Lease inducements are included in prepaid expenses and other assets in the accompanying consolidated balance sheets. Lease intangible assets and liabilities that have resulted from above-market and below-market leases that were acquired are amortized on a straight-line basis as decreases and increases, respectively, to rental revenue over the remaining non-cancellable term of the underlying leases. If a lease terminates prior to the expiration of its initial term, the unamortized portion of straight-line rents receivable, lease inducements and lease intangibles associated with that lease will be written off to rental revenue. In June 2015, we wrote-off as a reduction of base rent $0.4 million of unreserved straight-line rents receivable, $0.1 million of unamortized lease inducements and $1.0 million of unamortized lease intangibles related to a former customer in bankruptcy whose leases with us were rejected effective July 1, 2015 pursuant to an order made by the bankruptcy court. Balances, net of accumulated amortization, at December 31, 2015 and 2014 are as follows (in thousands): December 31, 2015 2014 Lease contracts above market value $ 20,500 $ 23,100 Accumulated amortization (14,471 ) (15,046 ) Lease contracts above market value, net $ 6,029 $ 8,054 Lease contracts below market value $ 24,175 $ 39,375 Accumulated amortization (20,043 ) (32,338 ) Lease contracts below market value, net $ 4,132 $ 7,037 Our policy is to record a reserve for losses on accounts receivable equal to the estimated uncollectible accounts. The estimate is based on our historical experience and a review of the current status of our receivables. As of December 31, 2015 and 2014 , we had one potentially uncollectible account that consisted of a note receivable from a customer in bankruptcy. The note balance as of December 31, 2015 and 2014 was $6.5 million and $6.6 million , respectively, which is recorded within rents and other receivables, net in our accompanying consolidated balance sheets. The note has been non-accrual over its term, and we applied interest received to the note principal balance totaling $1.2 million . As of December 31, 2015 and 2014 , respectively, we have established a reserve of $5.1 million and $4.9 million , including interest applied to principal. The note receivable, net of reserves and interest applied to the principal, was $1.4 million and $1.7 million as of December 31, 2015 and 2014 , respectively. In October 2015, a sale of our bankrupt customer's east coast business was consummated, and we continue to be reasonably assured that we will be able to collect the balance of the note receivable, net of reserve, as a claim in the bankruptcy. We also establish an appropriate allowance for doubtful accounts for receivables arising from the straight-lining of rents. These receivables arise from revenue recognized in excess of amounts currently due under the lease and are recorded as deferred rent, net in the accompanying consolidated balance sheets. As of December 31, 2014 , we had reserves against deferred rent relating to the leases with the now former customer in bankruptcy of $3.6 million . Due to the rejection of leases by this customer, we wrote off the reserved straight-line rent receivable for this customer in the second quarter of 2015. As of December 31, 2015 , we had reserves against deferred rent of $0.1 million . Customer leases generally contain provisions under which the customers reimburse us for a portion of operating expenses and real estate taxes incurred by the property. Recoveries from tenants are included in revenue in the accompanying consolidated statements of operations in the period the applicable expenditures are incurred. Most of our leases also provide us with a property management fee based on a percentage of base rent collected and property-level operating expenses, other than charges for power used by customers to run their servers and cool their space. Property management fees are included in base rent in the accompanying consolidated statements of operations in the applicable period in which they are earned.
Other Revenue [Policy Text Block]	Other Revenue Other revenue primarily consists of services provided to customers on a non-recurring basis. This includes projects such as the purchase and installation of circuits, racks, breakers and other customer requested items. Revenue is recognized on a completed contract basis when the project is finished and ready for the customer's use. This method is consistently applied for all periods presented. Costs of providing these services are included in other expenses in the accompanying consolidated statements of operations.
Income Tax, Policy [Policy Text Block]	Income Taxes DFT elected to be taxed as a REIT under the Internal Revenue Code of 1986, as amended (the “Code”), commencing with the taxable year ended December 31, 2007. In general, a REIT that meets certain organizational and operational requirements and distributes at least 90 percent of its REIT taxable income to its shareholders in a year will not be subject to income tax to the extent of the income it distributes. We currently qualify and intend to continue to qualify as a REIT under the Code. As a result, no provision for federal income taxes on income from continuing operations is required, except for taxes on certain property sales and on income, if any, of DF Technical Services, LLC, our taxable REIT subsidiary (“TRS”). If we fail to qualify as a REIT in any taxable year, we will be subject to federal income tax (including any applicable alternative minimum tax) on our income at regular corporate tax rates for the year in which we do not qualify and the succeeding four years. Although we expect to qualify for taxation as a REIT, we may be subject to state and local income and franchise taxes and to federal income and excise taxes on any undistributed income. As of December 31, 2015 and 2014 , we did not have any unrecognized tax benefits. We do not believe that there will be any material changes in our unrecognized tax positions over the next 12 months. We are subject to examination by the respective taxing authorities for the tax years 2012 through 2015. In general, a TRS may perform non-customary services for customers, hold assets that DFT cannot hold directly and generally may engage in any real estate or non-real estate related business. A TRS is subject to corporate federal and state income taxes on its taxable income at regular statutory tax rates. For the years ended December 31, 2015 and 2013 , we incurred no income taxes. For the year ended December 31, 2014 , we incurred $0.1 million of income taxes. We account for income taxes using the asset and liability method under which deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Valuation allowances are provided if, based upon the weight of the available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. As of December 31, 2015 , the TRS had a deferred tax asset of $4.6 million , comprised entirely of its net operating loss carryforward, and a deferred tax liability of $2.3 million , primarily comprised of a temporary depreciation difference, resulting in a net deferred tax asset of $2.3 million . We have recorded a full valuation allowance for this net deferred tax asset as of December 31, 2015 due to the uncertainty of the realizability of this asset. Accordingly, for the year December 31, 2015 , we recorded a deferred income tax credit of $0.2 million to reverse the cumulative deferred tax expense recorded as of December 31, 2014 , described below. The net operating loss carryforward of $4.6 million described above will begin to expire in 2031 if not utilized by then. As of December 31, 2014 , the TRS had a deferred tax asset of $5.5 million , comprised entirely of its net operating loss carryforward, and a deferred tax liability of $6.1 million , primarily comprised of a temporary depreciation difference, resulting in a net deferred tax liability of $0.6 million . For the year December 31, 2014 , we recorded deferred income tax expense of $0.2 million related to this deferred tax liability.
Redeemable Noncontrolling Interests—Operating Partnership / Redeemable Partnership Units [Policy Text Block]	Redeemable Noncontrolling Interests – Operating Partnership / Redeemable Partnership Units Redeemable noncontrolling interests – operating partnership, as presented on DFT’s consolidated balance sheets, represent the limited partnership interests in the Operating Partnership (“OP units”) held by individuals and entities other than DFT. These interests are also presented on the Operating Partnership’s consolidated balance sheets, referred to as “redeemable partnership units.” Accordingly, the following discussion related to redeemable noncontrolling interests – operating partnership of DFT refers equally to redeemable partnership units of the Operating Partnership. Redeemable noncontrolling interests – operating partnership, which require cash payment, or allow settlement in shares, but with the ability to deliver the shares outside of the control of DFT, are reported outside of the permanent equity section of the consolidated balance sheets of DFT and the Operating Partnership. Redeemable noncontrolling interests – operating partnership are adjusted for income, losses and distributions allocated to OP units not held by DFT (normal noncontrolling interest accounting amount). Adjustments to redeemable noncontrolling interests – operating partnership are recorded to reflect increases or decreases in the ownership of the Operating Partnership by holders of OP units, including the redemptions of OP units for cash or in exchange for shares of DFT’s common stock. If such adjustments result in redeemable noncontrolling interests – operating partnership being recorded at less than the redemption value of the OP units, redeemable noncontrolling interests – operating partnership are further adjusted to their redemption value (see Note 9). Redeemable noncontrolling interests – operating partnership are recorded at the greater of the normal noncontrolling interest accounting amount or redemption value. The following is a summary of activity for redeemable noncontrolling interests – operating partnership for the years ended December 31, 2015 , 2014 and 2013 (dollars in thousands): OP Units Number Amount Balance at December 31, 2012 18,786,806 $ 453,889 Net income attributable to redeemable noncontrolling interests – operating partnership — 5,214 Distributions declared — (15,050 ) Redemption of operating partnership units (3,115,269 ) (75,600 ) Adjustments to redeemable noncontrolling interests – operating partnership — 18,791 Balance at December 31, 2013 15,671,537 $ 387,244 Net income attributable to redeemable noncontrolling interests – operating partnership — 18,704 Distributions declared — (22,831 ) Redemption of operating partnership units (234,300 ) (6,100 ) Adjustments to redeemable noncontrolling interests – operating partnership — 136,117 Balance at December 31, 2014 15,437,237 $ 513,134 Net loss attributable to redeemable noncontrolling interests – operating partnership — (5,993 ) Distributions declared — (26,513 ) Redemption of operating partnership units (363,674 ) (9,544 ) Adjustments to redeemable noncontrolling interests – operating partnership — 8,105 Balance at December 31, 2015 15,073,563 $ 479,189 The following is a summary of activity for redeemable partnership units for the years ended December 31, 2015 , 2014 and 2013 (dollars in thousands): OP Units Number Amount Balance at December 31, 2012 18,786,806 $ 453,889 Redemption of operating partnership units (3,115,269 ) (75,600 ) Adjustments to redeemable partnership units — 8,955 Balance at December 31, 2013 15,671,537 $ 387,244 Redemption of operating partnership units (234,300 ) (6,100 ) Adjustments to redeemable partnership units — 131,990 Balance at December 31, 2014 15,437,237 $ 513,134 Redemption of operating partnership units (363,674 ) (9,544 ) Adjustments to redeemable partnership units — (24,401 ) Balance at December 31, 2015 15,073,563 $ 479,189 Net income is allocated to controlling interests and redeemable noncontrolling interests – operating partnership in accordance with the limited partnership agreement of the Operating Partnership. The following is a summary of net income attributable to controlling interests and transfers to redeemable noncontrolling interests – operating partnership for the years ended December 31, 2015 , 2014 and 2013 (dollars in thousands): Year ended December 31, 2015 2014 2013 Net income attributable to controlling interests $ 1,907 $ 105,907 $ 48,391 Transfers from noncontrolling interests: Net change in the Company’s common stock and additional paid in capital due to the redemption of OP units and other adjustments to redeemable noncontrolling interests – operating partnership 1,439 (130,017 ) 56,809 $ 3,346 $ (24,110 ) $ 105,200
Earnings Per Share of the REIT [Policy Text Block]	Earnings Per Share of DFT Basic earnings per share is calculated by dividing the net income attributable to common shares for the period by the weighted average number of common shares outstanding during the period using the two class method. Diluted earnings per share is calculated by dividing the net income attributable to common shares for the period by the weighted average number of common and dilutive securities outstanding during the period using the two class method.
Earnings Per Unit of the Operating Partnership [Policy Text Block]	Earnings Per Unit of the Operating Partnership Basic earnings per unit is calculated by dividing the net income attributable to common units for the period by the weighted average number of common units outstanding during the period using the two class method. Diluted earnings per unit is calculated by dividing the net income attributable to common units for the period by the weighted average number of common and dilutive securities outstanding during the period using the two class method.
Stock-based Compensation [Policy Text Block]	Stock-based Compensation We award stock-based compensation to employees and members of our Board of Directors in the form of common stock, restricted common stock and performance units. For each common stock award granted by DFT, the OP issues an equivalent common unit, which may be referred to herein as a common share, common stock, or a common unit. We estimate the fair value of the awards and recognize this value over the requisite service period. The fair value of restricted stock-based compensation is based on the market value of DFT’s common stock on the date of the grant. The fair value of options to purchase common stock is based on the Black-Scholes model. The fair value of performance units is based on a Monte Carlo simulation. Compensation paid with Company common shares, which is included in general and administrative expense on our consolidated statements of operations, totaled $5.3 million , $6.2 million and $6.1 million for the years ended December 31, 2015 , 2014 and 2013 , respectively. We capitalized $0.8 million , $0.7 million and $0.6 million of compensation paid with Company common shares to our data centers under development for the years ended December 31, 2015 , 2014 and 2013 , respectively.
New Accounting Pronouncements, Policy [Policy Text Block]	Recently Issued Accounting Pronouncements In May 2014, the FASB issued a comprehensive new revenue recognition standard that will supersede nearly all existing revenue recognition guidance under GAAP. The standard’s core principle is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. We will be required to apply the new standard in the first quarter of 2018 and are assessing whether the new standard will have a material effect on our financial position or results of operations. In August 2014, the FASB issued Accounting Standards Update No. 2014-15, Presentation of Financial Statements - Going Concern (Subtopic 205-40). Under this new guidance, management, will be required to perform a going concern evaluation similar to the auditor's evaluation required by standards issued by the Public Company Accounting Oversight Board and the American Institute of Certified Public Accountants. This evaluation will be required for both annual and interim reporting periods. We will be required to apply the new standard in the first quarter of 2017 and do not believe that the new standard will have a material effect on our financial position or results of operations. Recently Adopted Accounting Pronouncements In April 2015, the FASB issued ASU 2015-03, Interest—Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs . We have early-adopted this standard as of December 31, 2015 , which changed the presentation of debt issuance costs on in our accompanying consolidated balance sheets. The new guidance requires that deferred financing costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the debt liability rather than as an asset. However, the FASB subsequently issued ASU 2015-15, Interest—Imputation of Interest (Subtopic 835-30): Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of-Credit Arrangements , which allows an entity to continue to present line of credit issuance costs as an asset, regardless of whether there are any outstanding borrowings on the line of credit. Accordingly, for each of our recognized debt liabilities other than our Unsecured Credit Facility, we have reduced these balances by their respective deferred financing cost balances, net of accumulated amortization, and have applied this change retrospectively to all periods presented. Change in Accounting Principle As required by the new debt issuance cost guidance issued in April 2015, described above, we have retrospectively adjusted the presentation of deferred financing costs on our consolidated balance sheets for all prior periods presented, except for deferred loan costs relating to our Unsecured Credit Facility. The following table presents the prior period amounts that have been impacted by the new guidance and retrospectively adjusted on the consolidated balance sheet as of December 31, 2014: As of December 31, 2014 As Previously Reported Impact of Change in Accounting Principle As Adjusted and Currently Reported Deferred costs, net $ 38,495 $ 13,621 $ 24,874 Mortgage notes payable, net of deferred financing costs 115,000 1,333 113,667 Unsecured term loan, net of deferred financing costs 250,000 1,055 248,945 Unsecured notes payable, net of discount and deferred financing costs 600,000 11,233 588,767 The following table presents the impact of the change in accounting principal as of December 31, 2015 . The remaining balance of deferred financing costs included within deferred costs, net on our consolidated balance sheet relates to deferred financing costs, net of accumulated amortization, for our Unsecured Credit Facility of $3.2 million . As of December 31, 2015 Balance Prior to Change Impact of Change in Accounting Principle As Currently Reported Deferred costs, net $ 38,688 $ 14,914 $ 23,774 Mortgage notes payable, net of deferred financing costs 115,000 925 114,075 Unsecured term loan, net of deferred financing costs 250,000 828 249,172 Unsecured notes payable, net of discount and deferred financing costs 848,124 13,161 834,963

2. Significant Accounting Pol29

2. Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Schedule of Deferred Financing Costs [Table Text Block]	Balances of financing costs for our Unsecured Credit Facility, net of accumulated amortization, which are presented within deferred costs, net in our accompanying consolidated balance sheets at December 31, 2015 and 2014 , are as follows (in thousands): December 31, Financing costs presented within deferred costs, net 2015 2014 Financing costs $ 8,198 $ 7,448 Accumulated amortization (4,969 ) (3,779 ) Financing costs, net $ 3,229 $ 3,669 Balances of financing costs for our other recognized debt liabilities, net of accumulated amortization, which are presented as a reduction of each of the respective recognized debt liabilities in our accompanying consolidated balance sheets at December 31, 2015 and 2014 , are as follows (in thousands): December 31, Financing costs presented as a reduction of debt liability balances 2015 2014 Financing costs $ 20,531 $ 16,662 Accumulated amortization (5,618 ) (3,041 ) Financing costs, net $ 14,913 $ 13,621
Schedule of Leasing Costs Incurred [Table Text Block]	Leasing costs incurred for the years ended December 31, 2015 , 2014 and 2013 are as follows (in millions): Year ended December 31, 2015 2014 2013 Costs incurred for new leases $ 2.1 $ 2.0 $ 0.9 Costs incurred for renewals 1.2 0.2 1.2 Costs incurred for re-leases 0.9 2.0 — Total leasing costs incurred $ 4.2 $ 4.2 $ 2.1
Schedule of Deferred Leasing Costs [Table Text Block]	Balances, net of accumulated amortization, at December 31, 2015 and 2014 are as follows (in thousands): December 31, 2015 2014 Leasing costs $ 50,503 $ 52,358 Accumulated amortization (29,958 ) (31,153 ) Leasing costs, net $ 20,545 $ 21,205
Schedule of Lease Intangibles Above and Below Market Value [Table Text Block]	Balances, net of accumulated amortization, at December 31, 2015 and 2014 are as follows (in thousands): December 31, 2015 2014 Lease contracts above market value $ 20,500 $ 23,100 Accumulated amortization (14,471 ) (15,046 ) Lease contracts above market value, net $ 6,029 $ 8,054 Lease contracts below market value $ 24,175 $ 39,375 Accumulated amortization (20,043 ) (32,338 ) Lease contracts below market value, net $ 4,132 $ 7,037
Redeemable Noncontrolling Interest [Table Text Block]	The following is a summary of activity for redeemable noncontrolling interests – operating partnership for the years ended December 31, 2015 , 2014 and 2013 (dollars in thousands): OP Units Number Amount Balance at December 31, 2012 18,786,806 $ 453,889 Net income attributable to redeemable noncontrolling interests – operating partnership — 5,214 Distributions declared — (15,050 ) Redemption of operating partnership units (3,115,269 ) (75,600 ) Adjustments to redeemable noncontrolling interests – operating partnership — 18,791 Balance at December 31, 2013 15,671,537 $ 387,244 Net income attributable to redeemable noncontrolling interests – operating partnership — 18,704 Distributions declared — (22,831 ) Redemption of operating partnership units (234,300 ) (6,100 ) Adjustments to redeemable noncontrolling interests – operating partnership — 136,117 Balance at December 31, 2014 15,437,237 $ 513,134 Net loss attributable to redeemable noncontrolling interests – operating partnership — (5,993 ) Distributions declared — (26,513 ) Redemption of operating partnership units (363,674 ) (9,544 ) Adjustments to redeemable noncontrolling interests – operating partnership — 8,105 Balance at December 31, 2015 15,073,563 $ 479,189
Redeemable Partnership Units [Table Text Block]	The following is a summary of activity for redeemable partnership units for the years ended December 31, 2015 , 2014 and 2013 (dollars in thousands): OP Units Number Amount Balance at December 31, 2012 18,786,806 $ 453,889 Redemption of operating partnership units (3,115,269 ) (75,600 ) Adjustments to redeemable partnership units — 8,955 Balance at December 31, 2013 15,671,537 $ 387,244 Redemption of operating partnership units (234,300 ) (6,100 ) Adjustments to redeemable partnership units — 131,990 Balance at December 31, 2014 15,437,237 $ 513,134 Redemption of operating partnership units (363,674 ) (9,544 ) Adjustments to redeemable partnership units — (24,401 ) Balance at December 31, 2015 15,073,563 $ 479,189
Schedule of Net Income Attributable to Controlling Interests and Transfers From Redeemable Noncontrolling Interests Operating Partnership [Table Text Block]	The following is a summary of net income attributable to controlling interests and transfers to redeemable noncontrolling interests – operating partnership for the years ended December 31, 2015 , 2014 and 2013 (dollars in thousands): Year ended December 31, 2015 2014 2013 Net income attributable to controlling interests $ 1,907 $ 105,907 $ 48,391 Transfers from noncontrolling interests: Net change in the Company’s common stock and additional paid in capital due to the redemption of OP units and other adjustments to redeemable noncontrolling interests – operating partnership 1,439 (130,017 ) 56,809 $ 3,346 $ (24,110 ) $ 105,200
New Accounting Pronouncement, Early Adoption [Table Text Block]	The following table presents the prior period amounts that have been impacted by the new guidance and retrospectively adjusted on the consolidated balance sheet as of December 31, 2014: As of December 31, 2014 As Previously Reported Impact of Change in Accounting Principle As Adjusted and Currently Reported Deferred costs, net $ 38,495 $ 13,621 $ 24,874 Mortgage notes payable, net of deferred financing costs 115,000 1,333 113,667 Unsecured term loan, net of deferred financing costs 250,000 1,055 248,945 Unsecured notes payable, net of discount and deferred financing costs 600,000 11,233 588,767 The following table presents the impact of the change in accounting principal as of December 31, 2015 . The remaining balance of deferred financing costs included within deferred costs, net on our consolidated balance sheet relates to deferred financing costs, net of accumulated amortization, for our Unsecured Credit Facility of $3.2 million . As of December 31, 2015 Balance Prior to Change Impact of Change in Accounting Principle As Currently Reported Deferred costs, net $ 38,688 $ 14,914 $ 23,774 Mortgage notes payable, net of deferred financing costs 115,000 925 114,075 Unsecured term loan, net of deferred financing costs 250,000 828 249,172 Unsecured notes payable, net of discount and deferred financing costs 848,124 13,161 834,963

3. Real Estate Assets (Tables)

3. Real Estate Assets (Tables)	12 Months Ended
	Dec. 31, 2015
Real Estate [Abstract]
Schedule of Real Estate Properties [Table Text Block]	The following is a summary of our properties as of December 31, 2015 (dollars in thousands): Property Location Land Buildings and Improvements Construction in Progress and Land Held for Development Total Cost ACC2 Ashburn, VA $ 2,500 $ 154,192 $ 156,692 ACC3 Ashburn, VA 1,071 95,977 97,048 ACC4 Ashburn, VA 6,600 538,652 545,252 ACC5 Ashburn, VA 6,443 298,768 305,211 ACC6 Ashburn, VA 5,518 216,697 222,215 ACC7 Phase I-II Ashburn, VA 4,876 167,766 172,642 VA3 Reston, VA 9,000 179,021 188,021 VA4 Bristow, VA 6,800 149,499 156,299 CH1 Elk Grove Village, IL 23,611 358,739 382,350 CH2 Phase I Elk Grove Village, IL 3,998 71,847 75,845 NJ1 Phase I Piscataway, NJ 3,584 73,221 76,805 SC1 Santa Clara, CA 20,202 432,557 452,759 94,203 2,736,936 — 2,831,139 Construction in progress and land held for development (1 ) 300,939 300,939 $ 94,203 $ 2,736,936 $ 300,939 $ 3,132,078 (1) Properties located in Ashburn, VA (ACC7 Phases III-IV and ACC8); Piscataway, NJ (NJ1 Phase II), Elk Grove Village, IL (CH2 Phases II-III and CH3) and Santa Clara, CA (SC2). In the fourth quarter of 2015, we determined that it was more likely than not that we would sell our NJ1 data center prior to the end of its previously estimated useful life. We believe that it is unlikely that we will develop NJ1 Phase II prior to the sale. In August 2015, we acquired two parcels of land totaling 9.7 acres for a total purchase price of $8.6 million . These parcels are adjacent to our CH1 data center in Elk Grove Village, Illinois and are being held for the future development of CH3. In February 2016, we acquired two parcels of undeveloped land in Ashburn, Virginia. One parcel is a 35.4 acre site that we purchased for $15.6 million , and the other parcel is an 8.6 acre site that we purchased for $4.6 million . These parcels are being held for future development of ACC9, ACC10 and either a powered base shell or build-to-suit data center.
Major Components Of Properties And Useful Lives [Table Text Block]	The following presents the major components of our properties and the useful lives over which they are depreciated. Component Component Life (years) Land N/A Building improvements 40 Electrical infrastructure—power distribution units 20 Electrical infrastructure—uninterrupted power supply 25 Electrical infrastructure—switchgear/transformers 30 Fire protection 40 Security systems 20 Mechanical infrastructure—heating, ventilating and air conditioning 20 Mechanical infrastructure—chiller pumps/building automation 25 Mechanical infrastructure—chilled water storage and pipes 30

4. Intangible Assets and Liab31

4. Intangible Assets and Liabilities (Tables)	12 Months Ended
	Dec. 31, 2015
Leasing Costs [Member]
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]	As of December 31, 2015 , these assets have a weighted average remaining life of 6.6 years with estimated future amortization as follows (in thousands): Year Ending December 31, 2016 $ 4,167 2017 3,864 2018 3,336 2019 2,374 2020 1,868 2021 and thereafter 4,936 $ 20,545
Lease Contracts [Member]
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]	As of December 31, 2015 , our net lease intangible assets have a weighted average remaining life of 7.8 years for above market leases and 4.3 years for below market leases with estimated net future amortization (as an increase (decrease) to rental income) as follows (in thousands): Year Ending December 31, 2016 $ 464 2017 288 2018 56 2019 (421 ) 2020 (603 ) 2021 and thereafter (1,681 ) $ (1,897 )
Tenant Origination Costs [Member]
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]	As of December 31, 2015 , these assets have a weighted average remaining life of 2.6 years with estimated future amortization as follows (in thousands): Year Ending December 31, 2016 $ 1,243 2017 1,243 2018 746 $ 3,232

5. Leases (Tables)

5. Leases (Tables)	12 Months Ended
	Dec. 31, 2015
Leases [Abstract]
Schedule Of Customers Comprising More Than Ten Percent Of Consolidated Revenues [Table Text Block]	For the years ended December 31, 2015 , 2014 and 2013 , the following customers comprised more than 10.0% of our consolidated revenues: Microsoft Facebook Rackspace Yahoo! Year ended December 31, 2015 25.2 % 16.9 % 11.3 % 8.9 % Year ended December 31, 2014 21.6 % 17.4 % 12.4 % 10.9 % Year ended December 31, 2013 17.8 % 19.2 % 11.6 % 13.0 %
Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]	As of December 31, 2015 , future minimum lease payments to be received under noncancelable operating leases are as follows for the years ending December 31 (in thousands): 2016 $ 323,322 2017 327,062 2018 301,662 2019 237,931 2020 186,848 2021 and thereafter 482,871 $ 1,859,696

6. Debt (Tables)

6. Debt (Tables)	12 Months Ended
	Dec. 31, 2015
Debt Instrument [Line Items]
Schedule of Debt [Table Text Block]	Debt Summary as of December 31, 2015 and December 31, 2014 ($ in thousands) December 31, 2015 December 31, 2014 Amounts (1) % of Total Rates Maturities (years) Amounts (1) Secured $ 115,000 9 % 2.0 % 2.2 $ 115,000 Unsecured 1,100,000 91 % 4.9 % 5.6 910,000 Total $ 1,215,000 100 % 4.6 % 5.3 $ 1,025,000 Fixed Rate Debt: Unsecured Notes due 2021 $ 600,000 49 % 5.9 % 5.7 $ 600,000 Unsecured Notes due 2023 (2) 250,000 21 % 5.6 % 7.5 — Fixed Rate Debt $ 850,000 70 % 5.8 % 6.2 $ 600,000 Floating Rate Debt: Unsecured Credit Facility — — % — % 2.4 60,000 Unsecured Term Loan 250,000 21 % 1.7 % 3.6 250,000 ACC3 Term Loan 115,000 9 % 2.0 % 2.2 115,000 Floating Rate Debt 365,000 30 % 1.8 % 3.1 425,000 Total $ 1,215,000 100 % 4.6 % 5.3 $ 1,025,000 (1) Principal amounts exclude deferred financing costs. (2) Principal amount shown excludes original issue discount of $1.9 million .
Schedule of Maturities of Long-term Debt [Table Text Block]	A summary of our debt repayment schedule as of December 31, 2015 is as follows: Debt Maturity as of December 31, 2015 ($ in thousands) Year Fixed Rate (1) Floating Rate (1) Total (1) % of Total Rates 2016 $ — $ 3,750 (4) $ 3,750 0.3 % 2.0 % 2017 — 8,750 (4) 8,750 0.7 % 2.0 % 2018 — 102,500 (4) 102,500 8.4 % 2.0 % 2019 — 250,000 (5) 250,000 20.6 % 1.7 % 2020 — — — — % — % 2021 600,000 (2) — 600,000 49.4 % 5.9 % 2022 — — — — % — % 2023 250,000 (3) — 250,000 20.6 % 5.6 % Total $ 850,000 $ 365,000 $ 1,215,000 100 % 4.6 % (1) Principal amounts exclude deferred financing costs. (2) The 5.875% Unsecured Notes due 2021 mature on September 15, 2021 . (3) The 5.625% Unsecured Notes due 2023 mature on June 15, 2023 . Principal amount excludes original issue discount of $1.9 million as of December 31, 2015 . (4) The ACC3 Term Loan matures on March 27, 2018 with no extension option. Quarterly principal payments of $1.25 million begin on April 1, 2016 , increase to $2.5 million on April 1, 2017 and continue through maturity. (5) The Unsecured Term Loan matures on July 21, 2019 with no extension option.
Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Schedule Of Term Loan Interest Rate Margin Applicable By Indebtedness Level [Table Text Block] [Table Text Block]	Prior to our receiving an investment grade credit rating, the applicable margin added to LIBOR and the base rate is based on the table below. Applicable Margin Pricing Level Ratio of Total Indebtedness to Gross Asset Value LIBOR Rate Loans Base Rate Loans Level 1 Less than or equal to 35% 1.50 % 0.50 % Level 2 Greater than 35% but less than or equal to 40% 1.60 % 0.60 % Level 3 Greater than 40% but less than or equal to 45% 1.75 % 0.75 % Level 4 Greater than 45% but less than or equal to 52.5% 1.90 % 0.90 % Level 5 Greater than 52.5% 2.10 % 1.10 %
Schedule Of Credit Rating For Unsecured Term Loan [Table Text Block] [Table Text Block]	The terms of the Unsecured Term Loan also provide that, in the event we receive an investment grade credit rating, borrowings under the loan will bear interest based on the table below. Applicable Margin Credit Rating Level Credit Rating LIBOR Rate Loans Base Rate Loans Level 1 Greater than or equal to A- by S&P or A3 by Moody’s 0.825 % 0.00 % Level 2 Greater than or equal to BBB+ by S&P or Baa1 by Moody’s 0.875 % 0.00 % Level 3 Greater than or equal to BBB by S&P or Baa2 by Moody’s 1.00 % 0.00 % Level 4 Greater than or equal to BBB- by S&P or Baa3 by Moody’s 1.25 % 0.25 % Level 5 Less than BBB- by S&P or Baa3 by Moody’s 1.65 % 0.65 %
Unsecured Credit Facility [Member]
Debt Instrument [Line Items]
Schedule Of Line of Credit Interest Rate Margin Applicable By Indebtedness Level [Table Text Block]	Prior to our receiving an investment grade credit rating, the applicable margin added to LIBOR and the base rate is based on the table below. Applicable Margin Pricing Level Ratio of Total Indebtedness to Gross Asset Value LIBOR Rate Loans Base Rate Loans Level 1 Less than or equal to 35% 1.55 % 0.55 % Level 2 Greater than 35% but less than or equal to 40% 1.65 % 0.65 % Level 3 Greater than 40% but less than or equal to 45% 1.80 % 0.80 % Level 4 Greater than 45% but less than or equal to 52.5% 1.95 % 0.95 % Level 5 Greater than 52.5% 2.15 % 1.15 %
Schedule Of Credit Rating for Line of Credit [Table Text Block]	In the event we receive an investment grade credit rating, borrowings under the facility will bear interest based on the table below. Applicable Margin Credit Rating Level Credit Rating LIBOR Rate Loans Base Rate Loans Level 1 Greater than or equal to A- by S&P or A3 by Moody’s 0.875 % 0.00 % Level 2 Greater than or equal to BBB+ by S&P or Baa1 by Moody’s 0.925 % 0.00 % Level 3 Greater than or equal to BBB by S&P or Baa2 by Moody’s 1.05 % 0.05 % Level 4 Greater than or equal to BBB- by S&P or Baa3 by Moody’s 1.30 % 0.30 % Level 5 Less than BBB- by S&P or Baa3 by Moody’s 1.70 % 0.70 %
Unsecured Notes due 2021 [Member]
Debt Instrument [Line Items]
Debt Instrument Redemption [Table Text Block]	The Unsecured Notes due 2021 may be redeemed at the Operating Partnership's option, in whole or in part, at any time, on and after September 15, 2016 at the following redemption prices (expressed as percentages of the principal amount thereof) if redeemed during the 12-month period commencing September 15 of the years indicated below, in each case together with accrued and unpaid interest to the date of redemption: Year Redemption Price 2016 104.406 % 2017 102.938 % 2018 101.469 % 2019 and thereafter 100.000 %
Unsecured Notes due 2023 [Member]
Debt Instrument [Line Items]
Debt Instrument Redemption [Table Text Block]	The Unsecured Notes due 2023 may be redeemed at the Operating Partnership's option, in whole or in part, at any time, on and after June 15, 2018 at the following redemption prices (expressed as percentages of the principal amount thereof) if redeemed during the 12-month period commencing June 15 of the years indicated below, in each case together with accrued and unpaid interest to the date of redemption: Year Redemption Price 2018 104.219 % 2019 102.813 % 2020 101.406 % 2021 and thereafter 100.000 %

10. Preferred Stock (Tables)

10. Preferred Stock (Tables)	12 Months Ended
	Dec. 31, 2015
Series A Preferred Stock [Member]
Preferred Stock Dividend [Line Items]
Schedule of Preferred Stock Dividend [Table Text Block]	For the year ended December 31, 2013 , DFT declared and paid the following cash dividends on its Series A Preferred Stock, of which the OP paid equivalent distributions on its preferred units: Record Date Payment Date Cash Dividend Ordinary Taxable Dividend (Unaudited) Nontaxable Return of Capital Distributions (Unaudited) 4/5/2013 4/15/2013 $ 0.4921875 $ 0.4921875 $ 0.00 7/5/2013 7/15/2013 0.4921875 0.4921875 0.00 10/4/2013 10/15/2013 0.4921875 0.4921875 0.00 12/27/2013 1/15/2014 0.4921875 0.4921875 0.00 $ 1.9687500 $ 1.9687500 $ 0.00 For the year ended December 31, 2014 , DFT declared and paid the following cash dividends on its Series A Preferred Stock, of which the OP paid equivalent distributions on its preferred units: Record Date Payment Date Cash Dividend Ordinary Taxable Dividend (Unaudited) Nontaxable Return of Capital Distributions (Unaudited) 4/4/2014 4/15/2014 $ 0.4921875 $ 0.4921875 $ 0.00 7/3/2014 7/15/2014 0.4921875 0.4921875 0.00 10/3/2014 10/15/2014 0.4921875 0.4921875 0.00 12/30/2014 1/15/2015 0.4921875 0.4921875 0.00 $ 1.9687500 $ 1.9687500 $ 0.00 For the year ended December 31, 2015 , DFT declared and paid the following cash dividends on its Series A Preferred Stock, of which the OP paid equivalent distributions on its preferred units: Record Date Payment Date Cash Dividend Ordinary Taxable Dividend (Unaudited) Nontaxable Return of Capital Distributions (Unaudited) 4/2/2015 4/15/2015 $ 0.4921875 $ 0.4921875 $ 0.00 7/2/2015 7/15/2015 0.4921875 0.4921875 0.00 10/2/2015 10/15/2015 0.4921875 0.4921875 0.00 12/30/2015 1/15/2016 0.4921875 0.4921875 0.00 $ 1.9687500 $ 1.9687500 $ 0.00
Series B Preferred Stock [Member]
Preferred Stock Dividend [Line Items]
Schedule of Preferred Stock Dividend [Table Text Block]	For the year ended December 31, 2013 , DFT declared and paid the following cash dividends on its Series B Preferred Stock, of which the OP paid equivalent distributions on its preferred units: Record Date Payment Date Cash Dividend Ordinary Taxable Dividend (Unaudited) Nontaxable Return of Capital Distributions (Unaudited) 4/5/2013 4/15/2013 $ 0.4765625 $ 0.4765625 $ 0.00 7/5/2013 7/15/2013 0.4765625 0.4765625 0.00 10/4/2013 10/15/2013 0.4765625 0.4765625 0.00 12/27/2013 1/15/2014 0.4765625 0.4765625 0.00 $ 1.9062500 $ 1.9062500 $ 0.00 For the year ended December 31, 2015 , DFT declared and paid the following cash dividends on its Series B Preferred Stock, of which the OP paid equivalent distributions on its preferred units: Record Date Payment Date Cash Dividend Ordinary Taxable Dividend (Unaudited) Nontaxable Return of Capital Distributions (Unaudited) 4/2/2015 4/15/2015 $ 0.4765625 $ 0.4765625 $ 0.00 7/2/2015 7/15/2015 0.4765625 0.4765625 0.00 10/2/2015 10/15/2015 0.4765625 0.4765625 0.00 12/30/2015 1/15/2016 0.4765625 0.4765625 0.00 $ 1.9062500 $ 1.9062500 $ 0.00 For the year ended December 31, 2014 , DFT declared and paid the following cash dividends on its Series B Preferred Stock, of which the OP paid equivalent distributions on its preferred units: Record Date Payment Date Cash Dividend Ordinary Taxable Dividend (Unaudited) Nontaxable Return of Capital Distributions (Unaudited) 4/4/2014 4/15/2014 $ 0.4765625 $ 0.4765625 $ 0.00 7/3/2014 7/15/2014 0.4765625 0.4765625 0.00 10/3/2014 10/15/2014 0.4765625 0.4765625 0.00 12/30/2014 1/15/2015 0.4765625 0.4765625 0.00 $ 1.9062500 $ 1.9062500 $ 0.00

11. Stockholders Equity of th35

11. Stockholders Equity of the REIT and Partners Capital of the OP (Tables)	12 Months Ended
	Dec. 31, 2015
Stockholders’ Equity of the REIT and Partners’ Capital of the OP [Abstract]
Schedule Of Common Stock Dividend [Table Text Block]	For the year ended December 31, 2013, DFT declared and paid the following cash dividends totaling $0.95 per share on its common stock, of which the OP paid equivalent distributions on OP units: Record Date Payment Date Cash Dividend Ordinary Taxable Dividend (Unaudited) Nontaxable Return of Capital Distributions (Unaudited) 04/05/2013 04/15/2013 $ 0.20 $ 0.172 $ 0.028 07/05/2013 07/15/2013 0.25 0.214 0.036 10/04/2013 10/15/2013 0.25 0.214 0.036 12/27/2013 01/15/2014 0.25 — 0.000 $ 0.95 $ 0.600 $ 0.100 For the year ended December 31, 2014 , DFT declared and paid the following cash dividends totaling $1.47 per share on its common stock, of which the OP paid equivalent distributions on OP units: Record Date Payment Date Cash Dividend Ordinary Taxable Dividend (Unaudited) Nontaxable Return of Capital Distributions (Unaudited) 04/04/2014 04/15/2014 $ 0.35 $ 0.35 $ — 07/03/2014 07/15/2014 0.35 0.35 — 10/03/2014 10/15/2014 0.35 0.35 — 12/30/2014 01/15/2015 0.42 0.39 — $ 1.47 $ 1.44 $ — For the year ended December 31, 2015 , DFT declared and paid the following cash dividends totaling $1.73 per share on its common stock, of which the OP paid equivalent distributions on OP units: Record Date Payment Date Cash Dividend Ordinary Taxable Dividend (Unaudited) Nontaxable Return of Capital Distributions (Unaudited) 04/02/2015 04/15/2015 $ 0.42 $ 0.42 $ — 07/02/2015 07/15/2015 0.42 0.42 — 10/02/2015 10/15/2015 0.42 0.42 — 12/30/2015 01/16/2016 0.47 0.33 — $ 1.73 $ 1.59 $ —

12. Equity Compensation Plan (T

12. Equity Compensation Plan (Tables)	12 Months Ended
	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Unvested Restricted Stock Units Roll Forward [Table Text Block]	The following table sets forth the number of unvested shares of restricted stock and the weighted average fair value of these shares at the date of grant: Shares of Restricted Stock Weighted Average Fair Value at Date of Grant Unvested balance at December 31, 2012 297,919 $ 22.31 Granted 203,241 $ 22.82 Vested (162,353 ) $ 21.73 Forfeited (34,843 ) $ 22.86 Unvested balance at December 31, 2013 303,964 $ 22.89 Granted 149,608 $ 25.63 Vested (125,798 ) $ 23.02 Forfeited (3,785 ) $ 23.98 Unvested balance at December 31, 2014 323,989 $ 24.10 Granted 171,475 $ 32.12 Vested (138,585 ) $ 23.87 Forfeited (7,737 ) $ 28.71 Unvested balance at December 31, 2015 349,142 $ 28.02
Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]	A summary of our stock option activity under the applicable equity incentive plan for the years ended December 31, 2015 , 2014 and 2013 is presented in the tables below. Number of Options Weighted Average Exercise Price Under option, December 31, 2012 2,076,781 $ 15.17 Granted 374,214 $ 22.62 Exercised (250,472 ) $ 6.83 Forfeited (100,613 ) $ 22.83 Under option, December 31, 2013 2,099,910 $ 17.13 Granted — $ — Exercised (507,056 ) $ 10.95 Forfeited — $ — Under option, December 31, 2014 1,592,854 $ 19.09 Granted — $ — Exercised (362,642 ) $ 21.87 Forfeited — $ — Under option, December 31, 2015 1,230,212 $ 18.28 Shares Subject to Option Total Unearned Compensation Weighted Average Vesting Period Weighted Average Remaining Contractual Term As of December 31, 2013 2,099,910 $ 1.9 million 0.8 years 6.9 years As of December 31, 2014 1,592,854 $ 0.7 million 0.5 years 6.2 years As of December 31, 2015 1,230,212 $ 0.1 million 0.2 years 4.9 years
Schedule of Stock Options Roll Forward [Table Text Block]	The following table sets forth the number of unvested options as of December 31, 2015 , 2014 and 2013 and the weighted average fair value of these options at the grant date. Number of Options Weighted Average Fair Value at Date of Grant Unvested balance at December 31, 2012 809,991 $ 6.96 Granted 374,214 $ 4.75 Vested (399,481 ) $ 7.34 Forfeited (100,613 ) $ 5.55 Unvested balance at December 31, 2013 684,111 $ 5.73 Granted — $ — Vested (381,787 ) $ 6.28 Forfeited — $ — Unvested balance at December 31, 2014 302,324 $ 5.05 Granted — $ — Vested (263,553 ) $ 5.10 Forfeited — $ — Unvested balance at December 31, 2015 38,771 $ 4.75
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable [Table Text Block]	The following tables set forth the number of exercisable options as of December 31, 2015 , 2014 and 2013 and the weighted average fair value and exercise price of these options at the grant date. Number of Options Weighted Average Fair Value at Date of Grant Options Exercisable at December 31, 2012 1,266,790 $ 3.52 Vested 399,481 $ 7.34 Exercised (250,472 ) $ 2.35 Options Exercisable at December 31, 2013 1,415,799 $ 4.81 Vested 381,787 $ 6.28 Exercised (507,056 ) $ 3.54 Options Exercisable at December 31, 2014 1,290,530 $ 5.74 Vested 263,553 $ 5.10 Exercised (362,642 ) $ 6.34 Options Exercisable at December 31, 2015 1,191,441 $ 5.41 Exercisable Options Intrinsic Value Weighted Average Exercise Price Weighted Average Remaining Contractual Term As of December 31, 2013 1,415,799 $ 14.7 million $ 14.33 6.1 years As of December 31, 2014 1,290,530 $ 19.3 million $ 18.27 5.8 years As of December 31, 2015 1,191,441 $ 16.3 million $ 18.14 4.9 years
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]	The following table summarizes the assumptions used to value the stock options granted and the fair value of these options granted during the year ended December 31, 2013 . No stock options were granted during the years ended December 31, 2015 and 2014 . 2013 Number of options granted 374,214 Exercise price $ 22.62 Expected term (in years) 5 Expected volatility 34 % Expected annual dividend 4 % Risk-free rate 0.83 % Fair value at date of grant $1.8 million
Schedule of Share-based Payment Award, Performance Units, Valuation Assumptions [Table Text Block]	The following table summarizes the assumptions used to value, and the resulting fair and maximum values of, the performance units granted during the years ended December 31, 2015 , 2014 and 2013 . 2015 2014 2013 Number of performance units granted 48,674 110,441 60,468 Expected volatility 24 % 30 % 33 % Expected annual dividend 5 % 5 % 4 % Risk-free rate 1.06 % 0.74 % 0.40 % Performance unit fair value at date of grant $ 38.34 $ 33.50 $ 25.59 Total grant fair value at date of grant $1.9 million $3.7 million $1.5 million Maximum value of grant on vesting date based on closing price of DFT's stock at the date of grant $4.7 million $8.5 million $4.1 million

13. Earnings Per Share of the37

13. Earnings Per Share of the REIT (Tables)	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	The following table sets forth the reconciliation of basic and diluted average shares outstanding used in the computation of earnings per share of common stock (in thousands except for share and per share amounts): Twelve months ended December 31, 2015 2014 2013 Basic and Diluted Shares Outstanding Weighted average common shares – basic 65,184,013 65,486,108 64,645,316 Effect of dilutive securities — 600,271 828,723 Weighted average common shares – diluted 65,184,013 66,086,379 65,474,039 Calculation of Earnings per Share – Basic Net (loss) income attributable to common shares $ (25,338 ) $ 78,662 $ 21,146 Net income allocated to unvested restricted shares (599 ) (484 ) (267 ) Net (loss) income attributable to common shares, adjusted (25,937 ) 78,178 20,879 Weighted average common shares – basic 65,184,013 65,486,108 64,645,316 (Loss) earnings per common share – basic $ (0.40 ) $ 1.19 $ 0.32 Calculation of Earnings per Share – Diluted Net (loss) income attributable to common shares $ (25,937 ) $ 78,178 $ 21,146 Adjustments to redeemable noncontrolling interests — — 55 Adjusted net (loss) income available to common shares (25,937 ) 78,178 21,201 Weighted average common shares – diluted 65,184,013 66,086,379 65,474,039 (Loss) earnings per common share – diluted $ (0.40 ) $ 1.18 $ 0.32
Schedule of exclusions from diluted earnings per share/unit [Table Text Block]	The following table sets forth the amount of stock options and performance units that have been excluded from the calculation of diluted earnings per share (in millions): Twelve months ended December 31, 2015 2014 2013 Stock Options 0.6 — 0.6 Performance Units 0.1 0.1 0.1

14. Earnings Per Unit of the 38

14. Earnings Per Unit of the Operating Partnership (Tables)	12 Months Ended
	Dec. 31, 2015
Earnings per unit of the Operating Partnership [Line Items]
Schedule of basic and diluted units outstanding [Table Text Block]	The following table sets forth the reconciliation of basic and diluted average shares outstanding used in the computation of earnings per share of common stock (in thousands except for share and per share amounts): Twelve months ended December 31, 2015 2014 2013 Basic and Diluted Shares Outstanding Weighted average common shares – basic 65,184,013 65,486,108 64,645,316 Effect of dilutive securities — 600,271 828,723 Weighted average common shares – diluted 65,184,013 66,086,379 65,474,039 Calculation of Earnings per Share – Basic Net (loss) income attributable to common shares $ (25,338 ) $ 78,662 $ 21,146 Net income allocated to unvested restricted shares (599 ) (484 ) (267 ) Net (loss) income attributable to common shares, adjusted (25,937 ) 78,178 20,879 Weighted average common shares – basic 65,184,013 65,486,108 64,645,316 (Loss) earnings per common share – basic $ (0.40 ) $ 1.19 $ 0.32 Calculation of Earnings per Share – Diluted Net (loss) income attributable to common shares $ (25,937 ) $ 78,178 $ 21,146 Adjustments to redeemable noncontrolling interests — — 55 Adjusted net (loss) income available to common shares (25,937 ) 78,178 21,201 Weighted average common shares – diluted 65,184,013 66,086,379 65,474,039 (Loss) earnings per common share – diluted $ (0.40 ) $ 1.18 $ 0.32
Schedule of exclusions from diluted earnings per share/unit [Table Text Block]	The following table sets forth the amount of stock options and performance units that have been excluded from the calculation of diluted earnings per share (in millions): Twelve months ended December 31, 2015 2014 2013 Stock Options 0.6 — 0.6 Performance Units 0.1 0.1 0.1
Subsidiaries [Member]
Earnings per unit of the Operating Partnership [Line Items]
Schedule of basic and diluted units outstanding [Table Text Block]	The following table sets forth the reconciliation of basic and diluted average units outstanding used in the computation of earnings per unit: Twelve months ended December 31, 2015 2014 2013 Basic and Diluted Units Outstanding Weighted average common units – basic (includes redeemable partnership units and units of general and limited partners) 80,599,199 81,053,127 80,580,556 Effect of dilutive securities — 600,271 828,723 Weighted average common units – diluted 80,599,199 81,653,398 81,409,279
Schedule of exclusions from diluted earnings per share/unit [Table Text Block]	The following table sets forth the amount of stock options and performance units that have been excluded from the calculation of diluted earnings per unit (in millions): Twelve months ended December 31, 2015 2014 2013 Stock Options 0.6 — 0.6 Performance Units 0.1 0.1 0.1

17. Quarterly Financial Infor39

17. Quarterly Financial Information (Tables)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information [Table Text Block]	Three months ended December 31, 2015 September 30, 2015 June 30, 2015 March 31, 2015 Total revenue $ 115,923 $ 115,337 $ 113,826 $ 107,314 Net (loss) income (91,953 ) 30,393 31,141 26,333 Net (loss) income attributable to common shares (79,871 ) 19,062 19,668 15,803 Net (loss) income attributable to common shares per common share-basic (1.23 ) 0.29 0.30 0.24 Net (loss) income attributable to common shares per common share-diluted (1.23 ) 0.29 0.30 0.24 Three months ended December 31, 2014 September 30, 2014 June 30, 2014 March 31, 2014 Total revenue $ 107,977 $ 105,578 $ 101,950 $ 102,087 Net income 29,737 30,272 32,958 31,644 Net income attributable to common shares 18,536 18,960 21,121 20,045 Net income attributable to common shares per common share-basic (1) 0.28 0.29 0.32 0.30 Net income attributable to common shares per common share-diluted 0.28 0.29 0.32 0.30 (1) Amounts do not equal full year results due to rounding.

18. Supplemental Consolidatin40

18. Supplemental Consolidating Financial Data for Subsidiary Guarantors of the Unsecured Notes (Tables)	12 Months Ended
	Dec. 31, 2015
Supplemental Consolidating Financial Data for Subsidiary Guarantors of the Unsecured Notes [Abstract]
Schedule of Supplemental Consolidating Balance Sheets [Table Text Block]	DUPONT FABROS TECHNOLOGY, L.P. SUPPLEMENTAL CONSOLIDATING BALANCE SHEETS (in thousands except share data) December 31, 2015 Operating Partnership Subsidiary Guarantors Subsidiary Non-Guarantors Eliminations Consolidated Total ASSETS Income producing property: Land $ — $ 84,258 $ 9,945 $ — $ 94,203 Buildings and improvements — 2,399,016 337,920 — 2,736,936 — 2,483,274 347,865 — 2,831,139 Less: accumulated depreciation — (522,096 ) (38,741 ) — (560,837 ) Net income producing property — 1,961,178 309,124 — 2,270,302 Construction in progress and land held for development — 25,545 275,394 — 300,939 Net real estate — 1,986,723 584,518 — 2,571,241 Cash and cash equivalents 21,697 — 5,318 — 27,015 Rents and other receivables 1,391 7,563 634 — 9,588 Deferred rent — 122,830 6,111 — 128,941 Lease contracts above market value, net — 6,029 — — 6,029 Deferred costs, net 3,236 14,250 6,288 — 23,774 Investment in affiliates 2,546,465 — — (2,546,465 ) — Prepaid expenses and other assets 3,025 39,642 2,022 — 44,689 Total assets $ 2,575,814 $ 2,177,037 $ 604,891 $ (2,546,465 ) $ 2,811,277 LIABILITIES AND PARTNERS’ CAPITAL Liabilities: Line of credit $ — $ — $ — $ — $ — Mortgage notes payable, net of deferred financing costs — — 114,075 — 114,075 Unsecured term loan, net of deferred financing costs 249,172 — — — 249,172 Unsecured notes payable, net of discount and deferred financing costs 834,963 — — — 834,963 Accounts payable and accrued liabilities 4,516 23,615 4,170 — 32,301 Construction costs payable 43 293 21,707 — 22,043 Accrued interest payable 11,815 — 6 — 11,821 Distribution payable 43,906 — — — 43,906 Lease contracts below market value, net — 4,132 — — 4,132 Prepaid rents and other liabilities 12 62,630 4,835 — 67,477 Total liabilities 1,144,427 90,670 144,793 — 1,379,890 Redeemable partnership units 479,189 — — — 479,189 Commitments and contingencies — — — — — Limited Partners’ Capital: Series A cumulative redeemable perpetual preferred units, 7,400,000 issued and outstanding at December 31, 2015 185,000 — — — 185,000 Series B cumulative redeemable perpetual preferred units, 6,650,000 issued and outstanding at December 31, 2015 166,250 — — — 166,250 Common units, 65,443,277 issued and outstanding at December 31, 2015 594,927 2,086,367 460,098 (2,546,465 ) 594,927 General partner’s capital, 662,373 common units issued and outstanding at December 31, 2015 6,021 — — — 6,021 Total partners’ capital 952,198 2,086,367 460,098 (2,546,465 ) 952,198 Total liabilities & partners’ capital $ 2,575,814 $ 2,177,037 $ 604,891 $ (2,546,465 ) $ 2,811,277 DUPONT FABROS TECHNOLOGY, L.P. SUPPLEMENTAL CONSOLIDATING BALANCE SHEETS (in thousands except share data) December 31, 2014 Operating Partnership Subsidiary Guarantors Subsidiary Non-Guarantors Eliminations Consolidated Total ASSETS Income producing property: Land $ — $ 79,935 $ 3,858 $ — $ 83,793 Buildings and improvements — 2,427,706 195,833 — 2,623,539 — 2,507,641 199,691 — 2,707,332 Less: accumulated depreciation — (473,203 ) (31,666 ) — (504,869 ) Net income producing property — 2,034,438 168,025 — 2,202,463 Construction in progress and land held for development — 145,229 213,736 — 358,965 Net real estate — 2,179,667 381,761 — 2,561,428 Cash and cash equivalents 21,806 — 3,574 — 25,380 Rents and other receivables 1,775 5,513 825 — 8,113 Deferred rent — 139,542 2,823 — 142,365 Lease contracts above market value, net — 8,054 — — 8,054 Deferred costs, net 3,669 16,098 5,107 — 24,874 Investment in affiliates 2,547,049 — — (2,547,049 ) — Prepaid expenses and other assets 2,865 43,866 1,564 — 48,295 Total assets $ 2,577,164 $ 2,392,740 $ 395,654 $ (2,547,049 ) $ 2,818,509 LIABILITIES AND PARTNERS’ CAPITAL Liabilities: Line of credit $ 60,000 $ — $ — $ — $ 60,000 Mortgage notes payable, net of deferred financing costs — — 113,667 — 113,667 Unsecured term loan, net of deferred financing costs 248,945 — — — 248,945 Unsecured notes payable, net of discount and deferred financing costs 588,767 — — — 588,767 Accounts payable and accrued liabilities 4,432 19,580 2,961 — 26,973 Construction costs payable — 4,312 28,637 — 32,949 Accrued interest payable 10,754 — 5 — 10,759 Distribution payable 39,981 — — — 39,981 Lease contracts below market value, net — 7,037 — — 7,037 Prepaid rents and other liabilities 28 61,728 3,418 — 65,174 Total liabilities 952,907 92,657 148,688 — 1,194,252 Redeemable partnership units 513,134 — — — 513,134 Commitments and contingencies — — — — — Limited Partners’ Capital: Series A cumulative redeemable perpetual preferred units, 7,400,000 issued and outstanding at December 31, 2014 185,000 — — — 185,000 Series B cumulative redeemable perpetual preferred units, 6,650,000 issued and outstanding at December 31, 2014 166,250 — — — 166,250 Common units, 65,399,431 issued and outstanding at December 31, 2014 752,254 2,300,083 246,966 (2,547,049 ) 752,254 General partner’s capital, 662,373 common units issued and outstanding at December 31, 2014 7,619 — — — 7,619 Total partners’ capital 1,111,123 2,300,083 246,966 (2,547,049 ) 1,111,123 Total liabilities & partners’ capital $ 2,577,164 $ 2,392,740 $ 395,654 $ (2,547,049 ) $ 2,818,509
Schedule of Supplemental Consolidating Statements of Operations [Table Text Block]	Year ended December 31, 2015 Operating Partnership Subsidiary Guarantors Subsidiary Non-Guarantors Eliminations Consolidated Total Revenues: Base rent $ 18,061 $ 268,433 $ 30,302 $ (18,211 ) $ 298,585 Recoveries from tenants — 127,877 11,660 — 139,537 Other revenues — 1,787 12,621 (130 ) 14,278 Total revenues 18,061 398,097 54,583 (18,341 ) 452,400 Expenses: Property operating costs — 131,644 16,598 (18,191 ) 130,051 Real estate taxes and insurance — 19,942 1,393 — 21,335 Depreciation and amortization 43 94,371 9,630 — 104,044 General and administrative 17,574 57 433 — 18,064 Impairment on investment in real estate — 119,267 3,205 — 122,472 Other expenses 6,151 133 10,725 (150 ) 16,859 Total expenses 23,768 365,414 41,984 (18,341 ) 412,825 Operating (loss) income (5,707 ) 32,683 12,599 — 39,575 Interest income 60 — — — 60 Interest: Expense incurred (50,081 ) 1,327 8,184 — (40,570 ) Amortization of deferred financing costs (3,454 ) 107 196 — (3,151 ) Equity in earnings 55,096 — — (55,096 ) — Net (loss) income (4,086 ) 34,117 20,979 (55,096 ) (4,086 ) Preferred unit distributions (27,245 ) — — — (27,245 ) Net (loss) income attributable to common units $ (31,331 ) $ 34,117 $ 20,979 $ (55,096 ) $ (31,331 ) Year ended December 31, 2014 Operating Partnership Subsidiary Guarantors Subsidiary Non-Guarantors Eliminations Consolidated Total Revenues: Base rent $ 17,499 $ 267,454 $ 18,413 $ (17,650 ) $ 285,716 Recoveries from tenants — 115,185 9,668 — 124,853 Other revenues — 1,657 5,489 (123 ) 7,023 Total revenues 17,499 384,296 33,570 (17,773 ) 417,592 Expenses: Property operating costs — 123,140 11,822 (17,623 ) 117,339 Real estate taxes and insurance — 13,323 872 — 14,195 Depreciation and amortization 63 90,770 5,947 — 96,780 General and administrative 16,159 82 940 — 17,181 Other expenses 3,508 1,526 4,338 (150 ) 9,222 Total expenses 19,730 228,841 23,919 (17,773 ) 254,717 Operating (loss) income (2,231 ) 155,455 9,651 — 162,875 Interest income 115 — 1 — 116 Interest: Expense incurred (41,222 ) 4,323 3,200 — (33,699 ) Amortization of deferred financing costs (3,173 ) 273 (80 ) — (2,980 ) Loss on early extinguishment of debt (1,701 ) — — — (1,701 ) Equity in earnings 172,823 — — (172,823 ) — Net income (loss) 124,611 160,051 12,772 (172,823 ) 124,611 Preferred unit distributions (27,245 ) — — — (27,245 ) Net income attributable to common units $ 97,366 $ 160,051 $ 12,772 $ (172,823 ) $ 97,366 Year ended December 31, 2013 Operating Partnership Subsidiary Guarantors Subsidiary Non-Guarantors Eliminations Consolidated Total Revenues: Base rent $ 15,301 $ 248,719 $ 17,126 $ (15,451 ) $ 265,695 Recoveries from tenants — 94,794 9,477 — 104,271 Other revenues — 1,668 3,613 (138 ) 5,143 Total revenues 15,301 345,181 30,216 (15,589 ) 375,109 Expenses: Property operating costs 198 108,536 10,227 (15,439 ) 103,522 Real estate taxes and insurance — 13,931 449 — 14,380 Depreciation and amortization 81 88,556 4,421 — 93,058 General and administrative 15,605 97 559 — 16,261 Other expenses 778 304 2,718 (150 ) 3,650 Total expenses 16,662 211,424 18,374 (15,589 ) 230,871 Operating (loss) income (1,361 ) 133,757 11,842 — 144,238 Interest income (148 ) 20 — 265 137 Interest: Expense incurred (47,343 ) 351 814 (265 ) (46,443 ) Amortization of deferred financing costs (3,054 ) (167 ) (128 ) — (3,349 ) Loss on early extinguishment of debt (39,278 ) (1,700 ) — — (40,978 ) Equity in earnings 144,789 — — (144,789 ) — Net income (loss) 53,605 132,261 12,528 (144,789 ) 53,605 Preferred unit distributions (27,245 ) — — — (27,245 ) Net income attributable to common units $ 26,360 $ 132,261 $ 12,528 $ (144,789 ) $ 26,360
Schedule of Supplemental Consolidating Statements Of Cash Flows [Table Text Block]	DUPONT FABROS TECHNOLOGY, L.P. SUPPLEMENTAL CONSOLIDATING STATEMENTS OF CASH FLOWS (in thousands) Year ended December 31, 2015 Operating Partnership Subsidiary Guarantors Subsidiary Non-Guarantors Eliminations Consolidated Total Cash flow from operating activities Net cash (used in) provided by operating activities $ (55,999 ) $ 278,557 $ 32,466 $ — $ 255,024 Cash flow from investing activities Investments in real estate – development (415 ) (8,996 ) (207,928 ) — (217,339 ) Land acquisition costs — — (8,600 ) — (8,600 ) Investments in affiliates 68,074 (264,211 ) 196,137 — — Interest capitalized for real estate under development (27 ) (1,327 ) (10,210 ) — (11,564 ) Improvements to real estate — (3,401 ) (58 ) — (3,459 ) Additions to non-real estate property (93 ) (622 ) (38 ) — (753 ) Net cash provided by (used in) investing activities 67,539 (278,557 ) (30,697 ) — (241,715 ) Cash flow from financing activities Line of credit: Proceeds 120,000 — — — 120,000 Repayments (180,000 ) — — — (180,000 ) Unsecured notes payable: Proceeds 248,012 — — — 248,012 Payments of financing costs (4,715 ) — (25 ) — (4,740 ) Equity compensation (payments) proceeds 249 — — — 249 OP unit repurchases (31,912 ) — — — (31,912 ) Distributions (163,283 ) — — — (163,283 ) Net cash (used in) provided by financing activities (11,649 ) — (25 ) — (11,674 ) Net (decrease) increase in cash and cash equivalents (109 ) — 1,744 — 1,635 Cash and cash equivalents, beginning 21,806 — 3,574 — 25,380 Cash and cash equivalents, ending $ 21,697 $ — $ 5,318 $ — $ 27,015 DUPONT FABROS TECHNOLOGY, L.P. SUPPLEMENTAL CONSOLIDATING STATEMENTS OF CASH FLOWS (in thousands) Year ended December 31, 2014 Operating Partnership Subsidiary Guarantors Subsidiary Non-Guarantors Eliminations Consolidated Total Cash flow from operating activities Net cash (used in) provided by operating activities $ (40,234 ) $ 264,409 $ 20,339 $ — $ 244,514 Cash flow from investing activities Investments in real estate – development (404 ) (111,791 ) (153,179 ) — (265,374 ) Investments in affiliates 5,654 (146,188 ) 140,534 — — Interest capitalized for real estate under development (10 ) (4,323 ) (5,311 ) — (9,644 ) Improvements to real estate — (1,850 ) (66 ) — (1,916 ) Additions to non-real estate property (20 ) (257 ) (39 ) — (316 ) Net cash provided by (used in) investing activities 5,220 (264,409 ) (18,061 ) — (277,250 ) Cash flow from financing activities Line of credit: Proceeds 60,000 — — — 60,000 Unsecured term loan: Proceeds 96,000 — — — 96,000 Payments of financing costs (3,514 ) — (315 ) — (3,829 ) Equity compensation proceeds 4,363 — — — 4,363 Distributions (132,932 ) — — — (132,932 ) Net cash provided by (used in) financing activities 23,917 — (315 ) — 23,602 Net (decrease) increase in cash and cash equivalents (11,097 ) — 1,963 — (9,134 ) Cash and cash equivalents, beginning 32,903 — 1,611 — 34,514 Cash and cash equivalents, ending $ 21,806 $ — $ 3,574 $ — $ 25,380 Year ended December 31, 2013 Operating Partnership Subsidiary Guarantors Subsidiary Non-Guarantors Eliminations Consolidated Total Cash flow from operating activities Net cash (used in) provided by operating activities $ (48,725 ) $ 225,903 $ 16,583 $ — $ 193,761 Cash flow from investing activities Investments in real estate – development (9 ) (50,827 ) (78,496 ) — (129,332 ) Land Acquisition Costs — — (14,186 ) — (14,186 ) Investments in affiliates 62,508 (28,856 ) (33,652 ) — — Interest capitalized for real estate under development — (1,399 ) (2,375 ) — (3,774 ) Improvements to real estate — (5,513 ) (244 ) — (5,757 ) Additions to non-real estate property (6 ) (65 ) — — (71 ) Net cash provided by (used) in investing activities 62,493 (86,660 ) (128,953 ) — (153,120 ) Cash flow from financing activities Line of credit: Proceeds 102,000 — — — 102,000 Repayments (120,000 ) — — — (120,000 ) Mortgage notes payable: Proceeds — — 115,000 — 115,000 Lump sum payoffs — (138,300 ) — — (138,300 ) Repayments — (1,300 ) — — (1,300 ) Unsecured term loan: Proceeds 154,000 — — — 154,000 Unsecured notes payable: Proceeds 600,000 — — — 600,000 Repayments (550,000 ) — — — (550,000 ) Payments of financing costs (16,419 ) (4 ) (1,700 ) — (18,123 ) Payments for early extinguishment of debt (32,544 ) — — — (32,544 ) Equity compensation proceeds 1,711 — — — 1,711 Stock repurchases (37,792 ) — — — (37,792 ) Distributions (100,061 ) — — — (100,061 ) Net cash provided by (used in) financing activities 895 (139,604 ) 113,300 — (25,409 ) Net increase (decrease) in cash and cash equivalents 14,663 (361 ) 930 — 15,232 Cash and cash equivalents, beginning 18,240 361 681 — 19,282 Cash and cash equivalents, ending $ 32,903 $ — $ 1,611 $ — $ 34,514

Schedule II - Consolidated Al41

Schedule II - Consolidated Allowance for Doubtful Accounts (Tables)	12 Months Ended
	Dec. 31, 2015
Valuation and Qualifying Accounts Disclosure [Line Items]
Schedule of Valuation and Qualifying Accounts Disclosure [Text Block]	Balance at Beginning of Period Charges to Operations Net Recovery (Deductions) Balance at End of Period Allowance for doubtful accounts: Twelve months ended December 31, 2015 $ 8,520 $ 372 $ (3,651 ) $ 5,241 Twelve months ended December 31, 2014 3,700 4,829 (9 ) 8,520 Twelve months ended December 31, 2013 2,961 739 — 3,700
Allowance for Doubtful Accounts [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Schedule of Valuation and Qualifying Accounts Disclosure [Text Block]	Balance at Beginning of Period Charges to Operations Net Recovery (Deductions) Balance at End of Period Allowance for doubtful accounts: Twelve months ended December 31, 2015 $ 8,520 $ 372 $ (3,651 ) $ 5,241 Twelve months ended December 31, 2014 3,700 4,829 (9 ) 8,520 Twelve months ended December 31, 2013 2,961 739 — 3,700

Schedule III - Consolidated R42

Schedule III - Consolidated Real Estate and Accumulated Depreciation (Tables)	12 Months Ended
	Dec. 31, 2015
Real Estate and Accumulated Depreciation [Line Items]
Schedule Of Real Estate And Accumulated Depreciation [Table Text Block]	Encum-brances Initial Cost at Acquisition / Placement into Service Costs Capitalized Gross Carry Amount at Accumulated Year Year Land Building and improvements / Construction in progress Land Buildings & Land Building and improvements / Construction in progress Total Operating Properties ACC2 (1) $ — $ 2,500 $ 157,100 $ — $ (2,908 ) $ 2,500 $ 154,192 $ 156,692 $ (50,969 ) 2005 2001 ACC3 (2) 115,000 1,071 92,631 — 3,346 1,071 95,977 97,048 (32,723 ) 2006 2001 ACC4 (1) — 6,600 535,526 — 3,126 6,600 538,652 545,252 (157,174 ) 2007 2006 ACC5 (1) — 6,443 292,369 — 6,399 6,443 298,768 305,211 (60,744 ) 2009-2010 2007 ACC6 (1) — 5,518 215,235 — 1,462 5,518 216,697 222,215 (27,699 ) 2011-2013 2007 ACC7 Phase I and II — 4,876 167,766 — — 4,876 167,766 172,642 (4,806 ) 2014-2015 2011 CH1 (1) — 23,611 357,194 — 1,545 23,611 358,739 382,350 (70,407 ) 2008-2012 2007 CH2 Phase I — 3,998 71,778 — 69 3,998 71,847 75,845 (1,212 ) 2015 2013 NJ1 Phase I (1) (3) — 4,311 190,970 (727 ) (117,749 ) 3,584 73,221 76,805 — 2010 2007 SC1 (1) — 20,202 429,572 — 2,985 20,202 432,557 452,759 (39,013 ) 2011-2015 2007 VA3 (1) — 9,000 172,881 — 6,140 9,000 179,021 188,021 (65,458 ) 2003 2003 VA4 (1) — 6,800 140,575 — 8,924 6,800 149,499 156,299 (50,632 ) 2005 2005 Subtotal 115,000 94,930 2,823,597 (727 ) (86,661 ) 94,203 2,736,936 2,831,139 (560,837 ) Development Properties ACC7 Phases III and IV — 4,876 115,739 — — 4,876 115,739 120,615 — 2011 CH2 Phases II and III — 10,395 131,821 — — 10,395 131,821 142,216 — 2013 NJ1 Phase II (1) — 3,584 14,689 — — 3,584 14,689 18,273 — 2007 ACC8 — 3,785 458 — — 3,785 458 4,243 — 2007 CH3 — 8,305 15 — — 8,305 15 8,320 — 2015 SC2 (1) — 5,232 2,040 — — 5,232 2,040 7,272 — 2007 Subtotal — 36,177 264,762 — — 36,177 264,762 300,939 — Grand Total (4) $ 115,000 $ 131,107 $ 3,088,359 $ (727 ) $ (86,661 ) $ 130,380 $ 3,001,698 $ 3,132,078 $ (560,837 ) (1) The subsidiaries that own these data centers and development properties are guarantors of our Unsecured Notes due 2021 and 2023, our Unsecured Credit Facility and our Unsecured Term Loan. (2) The subsidiary that owns this data center is encumbered by our ACC3 Term Loan. (3) The carrying amount of our NJ1 data center was reduced as a result of an impairment charge that was recorded during the fourth quarter of 2015. This adjustment is reflected as a reduction to costs capitalized subsequent to acquisition / placement into service. (4) The aggregate gross cost of our properties for federal income tax purposes was $2.59 billion (unaudited) as of December 31, 2015 .
Schedule of Reconciliation Of Real Estate Assets and Accumulated Depreciation [Table Text Block]	2015 2014 2013 Real estate assets Balance, beginning of period $ 3,066,297 $ 2,799,010 $ 2,607,630 Additions - property acquisitions 8,600 — 14,186 Additions - improvements 221,588 267,357 177,194 Deductions - write-offs, impairments (164,407 ) (70 ) — Balance, end of period $ 3,132,078 $ 3,066,297 $ 2,799,010 Accumulated depreciation Balance, beginning of period $ 504,869 $ 413,394 $ 325,740 Additions - depreciation 97,988 91,545 87,654 Deductions - write-offs (42,020 ) (70 ) — Balance, end of period $ 560,837 $ 504,869 $ 413,394

1. Description of Business (Det

1. Description of Business (Details)	12 Months Ended
	Dec. 31, 2015
Subsidiary or Equity Method Investee [Line Items]
Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest	81.40%
Limited Liability Company (LLC) or Limited Partnership (LP), Managing Member or General Partner, Ownership Interest	1.00%

2. Significant Accounting Pol44

2. Significant Accounting Policies Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Significant Accounting Policies [Line Items]
Cash at Bank Held by Parent Company not Part of Operating Partnership	$ 4,200
Capitalized Interest and Deferred Financing Cost Amortization	12,300	$ 10,200	$ 4,000
Capitalized Internal Leasing And Development Costs	7,500	4,500	3,300
Depreciation	98,800	92,300	88,600
Tenant Origination Cost Amortization	2,000	3,100	3,100
Asset impairment charges	122,500	0	0
Write off of Deferred Debt Issuance Cost	0	1,701	40,978
Repayments of Notes Payable	0	0	138,300
Write off of Unamortized Leasing Costs	700
Amortization of Deferred Leasing Fees	4,900	4,100	4,100
Fuel Inventory	4,500	4,300
Write Off of Unreserved Straight-Line Rents Receivable	400
Write off of Unamortized Lease Inducements	100
Write off of Unamortized Lease Intangibles	1,000
Notes Receivable, Gross	6,500	6,600
Increase (Decrease) in Notes Receivables	(1,200)
Account receivable reserve	5,100	4,900
Notes Receivable, Net	1,400	1,700
Deferred Rent Reserve	100	3,600
Income Tax Expense (Benefit)	0	100	0
Deferred Tax Assets, Gross	4,600	5,500
Deferred Tax Liabilities, Gross	2,300	6,100
Deferred Tax Assets, Net	2,300
Deferred Income Tax Expense (Benefit)	(200)	200
Operating Loss Carryforwards	4,600
Deferred Tax Liabilities, Net		600
Allocated Share-based Compensation Expense	5,300	6,200	6,100
Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Capitalized Amount	$ 800	700	600
Building and Building Improvements [Member]
Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life	40 years
Minimum [Member] | Building and Building Improvements [Member]
Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life	10 years
Minimum [Member] | Personal Property [Member]
Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Maximum [Member] | Building and Building Improvements [Member]
Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life	40 years
Maximum [Member] | Personal Property [Member]
Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life	7 years
Revolving Credit Facility [Member]
Significant Accounting Policies [Line Items]
Write off of Deferred Debt Issuance Cost		300
Acc Five Term Loan [Member]
Significant Accounting Policies [Line Items]
Write off of Deferred Debt Issuance Cost			1,700
Repayments of Notes Payable			138,300
Unsecured Term Loan [Member]
Significant Accounting Policies [Line Items]
Write off of Deferred Debt Issuance Cost		1,400
Write Off Of Unamortized Debt Issuance Cost		$ 700
Unsecured Notes due 2017 [Member]
Significant Accounting Policies [Line Items]
Write off of Deferred Debt Issuance Cost			$ 6,700

2. Significant Accounting Pol45

2. Significant Accounting Policies Schedule of Deferred Financing Costs (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Assets [Member]
Significant Accounting Policies [Line Items]
Financing costs	$ 8,198	$ 7,448
Accumulated amortization	(4,969)	(3,779)
Financing costs, net	3,229	3,669
Liability [Member]
Significant Accounting Policies [Line Items]
Financing costs	20,531	16,662
Accumulated amortization	(5,618)	(3,041)
Financing costs, net	$ 14,913	$ 13,621

2. Significant Accounting Pol46

2. Significant Accounting Policies Schedule of Leasing Costs Incurred (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Leasing Costs Incurred [Line Items]
Payments for Leasing Costs	$ 4.2	$ 4.2	$ 2.1
Costs incurred for new leases
Schedule of Leasing Costs Incurred [Line Items]
Payments for Leasing Costs	2.1	2	0.9
Costs incurred for renewals
Schedule of Leasing Costs Incurred [Line Items]
Payments for Leasing Costs	1.2	0.2	1.2
Costs incurred for re-leases
Schedule of Leasing Costs Incurred [Line Items]
Payments for Leasing Costs	$ 0.9	$ 2	$ 0

2. Significant Accounting Pol47

2. Significant Accounting Policies Schedule of Deferred Leasing Costs (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Leasing costs	$ 50,503	$ 52,358
Accumulated amortization	(29,958)	(31,153)
Total	$ 20,545	$ 21,205

2. Significant Accounting Pol48

2. Significant Accounting Policies Schedule of Above and Below Market Lease Intangibles (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Lease contracts above market value	$ 20,500	$ 23,100
Accumulated amortization	(14,471)	(15,046)
Lease contracts above market value, net	6,029	8,054
Lease contracts below market value	24,175	39,375
Accumulated amortization	(20,043)	(32,338)
Lease contracts below market value, net	$ 4,132	$ 7,037

2. Significant Accounting Pol49

2. Significant Accounting Policies Schedule of Redeemable Noncontrolling Interests - Operating Partnership (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accounting Policies [Abstract]
Beginning Balance, units	15,437,237	15,671,537	18,786,806
Beginning Balance	$ 513,134	$ 387,244	$ 453,889
Net income attributable to redeemable noncontrolling interests - operating partnership	(5,993)	18,704	5,214
Distributions declared	$ (26,513)	$ (22,831)	$ (15,050)
Redemption of operating partnership units, shares	(363,674)	(234,300)	(3,115,269)
Redemption of operating partnership units	$ (9,544)	$ (6,100)	$ (75,600)
Adjustments to redeemable noncontrolling interests – operating partnership	$ 8,105	$ 136,117	$ 18,791
Ending Balance, units	15,073,563	15,437,237	15,671,537
Ending Balance	$ 479,189	$ 513,134	$ 387,244

2. Significant Accounting Pol50

2. Significant Accounting Policies Schedule of Redeemable Partnership Units (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Significant Accounting Policies [Line Items]
Beginning Balance, units	15,437,237	15,671,537	18,786,806
Beginning Balance	$ 513,134	$ 387,244	$ 453,889
Redemption of operating partnership units, shares	(363,674)	(234,300)	(3,115,269)
Redemption of operating partnership units	$ (9,544)	$ (6,100)	$ (75,600)
Ending Balance, units	15,073,563	15,437,237	15,671,537
Ending Balance	$ 479,189	$ 513,134	$ 387,244
Subsidiaries [Member]
Significant Accounting Policies [Line Items]
Beginning Balance, units	15,437,237	15,671,537	18,786,806
Beginning Balance	$ 513,134	$ 387,244	$ 453,889
Redemption of operating partnership units, shares	(363,674)	(234,300)	(3,115,269)
Redemption of operating partnership units	$ (9,544)	$ (6,100)	$ (75,600)
Adjustments to redeemable partnership units	$ (24,401)	$ 131,990	$ 8,955
Ending Balance, units	15,073,563	15,437,237	15,671,537
Ending Balance	$ 479,189	$ 513,134	$ 387,244

2. Significant Accounting Pol51

2. Significant Accounting Policies Schedule of Net Income Attributable to Controlling Interests and Transfers to Redeemable Noncontrolling Interests – Operating Partnership (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accounting Policies [Abstract]
Net income attributable to controlling interests	$ 1,907	$ 105,907	$ 48,391
Net change in the Company’s common stock and additional paid in capital due to the redemption of OP units and other adjustments to redeemable noncontrolling interests – operating partnership	1,439	(130,017)	56,809
Net Income Attributable to Controlling Interests and Transfers from Redeemable Noncontrolling Interests Operating Partnership	$ 3,346	$ (24,110)	$ 105,200

2. Significant Accounting Pol52

2. Significant Accounting Policies Schedule of New Accounting Pronouncement, Early Adoption (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
New Accounting Pronouncement, Early Adoption [Line Items]
Deferred costs, net	$ 23,774	$ 24,874
Mortgage notes payable	114,075	113,667
Unsecured Term Loan	249,172	248,945
Unsecured notes payable	834,963	588,767
Adjustments for New Accounting Principle, Early Adoption [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Deferred costs, net	38,688	38,495
Mortgage notes payable	115,000	115,000
Unsecured Term Loan	250,000	250,000
Unsecured notes payable	848,124	600,000
New Accounting Pronouncement, Early Adoption, Effect [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Deferred costs, net	14,914	13,621
Mortgage notes payable	925	1,333
Unsecured Term Loan	828	1,055
Unsecured notes payable	$ 13,161	$ 11,233

3. Real Estate Assets Summary o

3. Real Estate Assets Summary of Properties (Details) $ in Thousands	Feb. 02, 2016USD ($)a	Dec. 31, 2015USD ($)a		Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2012USD ($)
Real Estate Assets [Line Items]
Land		$ 94,203		$ 83,793
Buildings and improvements		2,736,936		2,623,539
Construction in progress and land held for development		300,939	[1]	358,965
Income producing property		2,831,139		2,707,332
Real Estate, Gross		3,132,078		$ 3,066,297	$ 2,799,010	$ 2,607,630
ACC2 [Member]
Real Estate Assets [Line Items]
Land		2,500
Buildings and improvements		$ 154,192
Construction in progress and land held for development
Income producing property		$ 156,692
ACC3 [Member]
Real Estate Assets [Line Items]
Land		1,071
Buildings and improvements		$ 95,977
Construction in progress and land held for development
Income producing property		$ 97,048
ACC4 [Member]
Real Estate Assets [Line Items]
Land		6,600
Buildings and improvements		$ 538,652
Construction in progress and land held for development
Income producing property		$ 545,252
ACC5 [Member]
Real Estate Assets [Line Items]
Land		6,443
Buildings and improvements		$ 298,768
Construction in progress and land held for development
Income producing property		$ 305,211
ACC6 [Member]
Real Estate Assets [Line Items]
Land		5,518
Buildings and improvements		$ 216,697
Construction in progress and land held for development
Income producing property		$ 222,215
ACC7 Phase I-II [Member]
Real Estate Assets [Line Items]
Land		4,876
Buildings and improvements		$ 167,766
Construction in progress and land held for development
Income producing property		$ 172,642
VA3 [Member]
Real Estate Assets [Line Items]
Land		9,000
Buildings and improvements		$ 179,021
Construction in progress and land held for development
Income producing property		$ 188,021
VA4 [Member]
Real Estate Assets [Line Items]
Land		6,800
Buildings and improvements		$ 149,499
Construction in progress and land held for development
Income producing property		$ 156,299
CH1 [Member]
Real Estate Assets [Line Items]
Land		23,611
Buildings and improvements		$ 358,739
Construction in progress and land held for development
Income producing property		$ 382,350
CH2 Phase I [Member]
Real Estate Assets [Line Items]
Land		3,998
Buildings and improvements		$ 71,847
Construction in progress and land held for development
Income producing property		$ 75,845
NJ1 Phase I [Member]
Real Estate Assets [Line Items]
Land		3,584
Buildings and improvements		$ 73,221
Construction in progress and land held for development
Income producing property		$ 76,805
SC1 [Member]
Real Estate Assets [Line Items]
Land		20,202
Buildings and improvements		$ 432,557
Construction in progress and land held for development
Income producing property		$ 452,759
Part of Chicago Center [Member]
Real Estate Assets [Line Items]
Purchase Of Undeveloped Parcel Of Land In Acres | a		9.7
Purchase Price of Undeveloped Land Parcel		$ 8,600
Adjacent to Ashburn Corporate Center [Member] | Subsequent Event [Member]
Real Estate Assets [Line Items]
Purchase Of Undeveloped Parcel Of Land In Acres | a	35.4
Purchase Price of Undeveloped Land Parcel	$ 15,600
Part of Ashburn Corporate Center [Member] | Subsequent Event [Member]
Real Estate Assets [Line Items]
Purchase Of Undeveloped Parcel Of Land In Acres | a	8.6
Purchase Price of Undeveloped Land Parcel	$ 4,600
[1]	(1)Properties located in Ashburn, VA (ACC7 Phases III-IV and ACC8); Piscataway, NJ (NJ1 Phase II), Elk Grove Village, IL (CH2 Phases II-III and CH3) and Santa Clara, CA (SC2). In the fourth quarter of 2015, we determined that it was more likely than not that we would sell our NJ1 data center prior to the end of its previously estimated useful life. We believe that it is unlikely that we will develop NJ1 Phase II prior to the sale.In August 2015, we acquired two parcels of land totaling 9.7 acres for a total purchase price of $8.6 million. These parcels are adjacent to our CH1 data center in Elk Grove Village, Illinois and are being held for the future development of CH3. In February 2016, we acquired two parcels of undeveloped land in Ashburn, Virginia. One parcel is a 35.4 acre site that we purchased for $15.6 million, and the other parcel is an 8.6 acre site that we purchased for $4.6 million. These parcels are being held for future development of ACC9, ACC10 and either a powered base shell or build-to-suit data center.

3. Real Estate Assets Schedule

3. Real Estate Assets Schedule of Major Components of Properties and Useful Lives (Details)	12 Months Ended
	Dec. 31, 2015
Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	40 years
Electrical Structure Power Distribution Units [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	20 years
Electrical Structure Uninterrupted Power Supply [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	25 years
Electrical Structure Switchgear Or Transformers [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	30 years
Fire Protection [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	40 years
Security Systems [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	20 years
Mechanical Structure Heating Ventilating And Air Conditioning [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	20 years
Mechanical Structure Chiller Pumps Or Building Automation [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	25 years
Mechanical Structure Chilled Water Storage And Pipes [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	30 years

4. Intangible Assets and Liab55

4. Intangible Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Total	$ 20,545	$ 21,205
Leasing Costs [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Life	6 years 219 days
2,016	$ 4,167
2,017	3,864
2,018	3,336
2,019	2,374
2,020	1,868
2021 and thereafter	4,936
Total	20,545
Lease Contracts
Finite-Lived Intangible Assets [Line Items]
2,016	464
2,017	288
2,018	56
2,019	(421)
2,020	(603)
2021 and thereafter	(1,681)
Total	$ (1,897)
Tenant Origination Costs [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Life	2 years 219 days
2,016	$ 1,243
2,017	1,243
2,018	746
Total	$ 3,232
Above Market Leases [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Life	7 years 292 days
Below Market Leases [Member]
Finite-Lived Intangible Assets [Line Items]
Weighted Average Remaining Life	4 years 110 days

5. Leases (Details)

5. Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Capital Leased Assets [Line Items]
Deferred rent, net	$ 128,941	$ 142,365
Microsoft [Member]
Capital Leased Assets [Line Items]
Deferred rent, net	(5,200)	(300)
Prepaid rents	9,800	8,300
Facebook [Member]
Capital Leased Assets [Line Items]
Deferred rent, net	42,500	43,600
Prepaid rents	6,800	6,400
Rackspace [Member]
Capital Leased Assets [Line Items]
Deferred rent, net	36,400	35,400
Prepaid rents	4,300	0
Yahoo [Member]
Capital Leased Assets [Line Items]
Deferred rent, net	7,500	10,800
Prepaid rents	$ 2,500	$ 3,800

5. Leases Schedule of Customers

5. Leases Schedule of Customers Comprising More Than 10% Of Consolidated Revenues (Details)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Microsoft [Member]
Property Subject to or Available for Operating Lease [Line Items]
Customers Comprising More Than Ten Percentage Of Consolidated Revenues	0.252	0.216	0.178
Facebook [Member]
Property Subject to or Available for Operating Lease [Line Items]
Customers Comprising More Than Ten Percentage Of Consolidated Revenues	0.169	0.174	0.192
Rackspace [Member]
Property Subject to or Available for Operating Lease [Line Items]
Customers Comprising More Than Ten Percentage Of Consolidated Revenues	0.113	0.124	0.116
Yahoo [Member]
Property Subject to or Available for Operating Lease [Line Items]
Customers Comprising More Than Ten Percentage Of Consolidated Revenues	0.089	0.109	0.130
Minimum [Member]
Property Subject to or Available for Operating Lease [Line Items]
Customers Comprising More Than Ten Percentage Of Consolidated Revenues	0.100

5. Leases Schedule of Operating

5. Leases Schedule of Operating Lease Future Minimum Lease Payments (Details) $ in Thousands	Dec. 31, 2015USD ($)
Schedule of Operating Lease Future Minimum Lease Payments [Line Items]
2,016	$ 323,322
2,017	327,062
2,018	301,662
2,019	237,931
2,020	186,848
2021 and thereafter	482,871
Total	$ 1,859,696

6. Debt Summary (Details)

6. Debt Summary (Details) $ in Thousands	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Debt Instrument [Line Items]
Mortgage notes payable	$ 114,075	$ 113,667
Unsecured Term Loan	249,172	248,945
Long-term Debt	1,215,000	1,025,000
Unsecured notes payable	834,963	588,767
Line of credit	$ 0	60,000
Total Debt in Percentage	100.00%
Debt, Weighted Average Interest Rate	4.60%
Long Term Debt, Weighted Average Maturity in Years	5.3
Fixed Rate Debt [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Fixed Interest, Amount	$ 850,000	600,000
Percentage of Total Debt	70.00%
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate	5.80%
FixedInterestDebtMaturityInYears	6.2
Unsecured Notes due 2021 [Member]
Debt Instrument [Line Items]
Unsecured notes payable		600,000
Percentage of Total Debt	49.00%
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate	5.875%
Unsecured Debt Maturity, in Years	5.7
Unsecured Notes due 2023 [Member]
Debt Instrument [Line Items]
Unsecured notes payable	$ 250,000	0
Percentage of Total Debt	21.00%
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate	5.60%
Unsecured Debt Maturity, in Years	7.5
Floating Rate Debt [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Amount	$ 365,000	425,000
Percentage of Total Debt	30.00%
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	1.80%
VariableInterestDebtMaturityInYears	3.1
Unsecured Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit	$ 0	60,000
Percentage of Total Debt	0.00%
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	0.00%
Unsecured Debt Maturity, in Years	2.4
Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Unsecured Term Loan	$ 250,000	250,000
Percentage of Total Debt	21.00%
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	1.70%
Unsecured Debt Maturity, in Years	3.6
AccThreeTermLoan [Member]
Debt Instrument [Line Items]
Term Loan	$ 115,000	115,000
Percentage of Total Debt	9.00%
Long-term Debt, Percentage Bearing Variable Interest, Percentage Rate	2.00%
Secured Debt Maturity, in Years	2.2
Secured Debt [Member]
Debt Instrument [Line Items]
Mortgage notes payable	$ 115,000	115,000
Percentage of Total Debt	9.00%
Long-Term Debt, Secured Interest Rate	2.00%
Secured Debt Maturity, in Years	2.2
Unsecured Debt [Member]
Debt Instrument [Line Items]
Unsecured Term Loan	$ 1,100,000	$ 910,000
Percentage of Total Debt	91.00%
Long-Term Debt, Unsecured Interest Rate	4.90%
Unsecured Debt Maturity, in Years	5.6
Unsecured Notes due 2023 [Member]
Debt Instrument [Line Items]
Unsecured notes payable	$ 250,000
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate	5.625%
Debt Instrument, Unamortized Discount	$ 1,900

6. Debt Unsecured Credit Facili

6. Debt Unsecured Credit Facility (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)	Feb. 19, 2016USD ($)	Jun. 30, 2015USD ($)	Dec. 31, 2014USD ($)
Debt Instrument [Line Items]
Line of credit	$ 0			$ 60,000
Unsecured Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 700,000		$ 560,000
Line of Credit Facility, Expiration Date	May 13, 2018
Extension Option On Debt Maturity Years	1
Basis Points Extension Fee On Total Commitment	15
Line of Credit Facility, Maximum Borrowing Capacity	$ 800,000
Facility amount available for Letters of Credit	35,000
Letters of Credit Outstanding, Amount	100
Line of credit	$ 0
Unsecured Credit Facility [Member] | Maximum [Member]
Debt Instrument [Line Items]
Unsecured Debt To Unencumbered Assets	60.00%
Ratio of Total Indebtedness To Gross Assets Value	60.00%
Unsecured Credit Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Income from Unencumbered Assets To Unsecured Debt	12.50%
Fixed Charge Coverage Ratio	1.70
Tangible Net Worth Amount	$ 1,300,000
Percentage Of Equity Offerings And Interests In Operating Partnerships To Be Added To Tangible Net Worth Threshold	80.00%
Subsequent Event [Member] | Unsecured Credit Facility [Member]
Debt Instrument [Line Items]
Line of credit		$ 40,000

6. Debt Applicable Margin of Un

6. Debt Applicable Margin of Unsecured Credit Facility (Details) - Unsecured Credit Facility [Member]	12 Months Ended
	Dec. 31, 2015
Maximum [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	60.00%
Pricing Level 1 [Member] | Libor Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.55%
Pricing Level 1 [Member] | Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.55%
Pricing Level 1 [Member] | Maximum [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	35.00%
Pricing Level 2 [Member] | Libor Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.65%
Pricing Level 2 [Member] | Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.65%
Pricing Level 2 [Member] | Maximum [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	40.00%
Pricing Level 2 [Member] | Minimum [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	35.00%
Pricing Level 3 [Member] | Libor Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.80%
Pricing Level 3 [Member] | Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.80%
Pricing Level 3 [Member] | Maximum [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	45.00%
Pricing Level 3 [Member] | Minimum [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	40.00%
Pricing Level 4 [Member] | Libor Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.95%
Pricing Level 4 [Member] | Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.95%
Pricing Level 4 [Member] | Maximum [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	52.50%
Pricing Level 4 [Member] | Minimum [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	45.00%
Pricing Level 5 [Member] | Libor Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.15%
Pricing Level 5 [Member] | Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.15%
Pricing Level 5 [Member] | Minimum [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	52.50%

6. Debt Credit Rating for Unsec

6. Debt Credit Rating for Unsecured Credit Facility (Details) - Unsecured Credit Facility [Member]	12 Months Ended
	Dec. 31, 2015
Credit Rating Level 1 [Member] | Moody's, A3 Rating [Member] | Libor Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.875%
Credit Rating Level 1 [Member] | Moody's, A3 Rating [Member] | Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.00%
Credit Rating Level 2 [Member] | Moody's, Baa1 Rating [Member] | Libor Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.925%
Credit Rating Level 2 [Member] | Moody's, Baa1 Rating [Member] | Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.00%
Credit Rating Level 3 [Member] | Moody's, Baa2 Rating [Member] | Libor Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.05%
Credit Rating Level 3 [Member] | Moody's, Baa2 Rating [Member] | Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.05%
Credit Rating Level 4 [Member] | Moody's, Baa3 Rating [Member] | Libor Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.30%
Credit Rating Level 4 [Member] | Moody's, Baa3 Rating [Member] | Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.30%
Credit Rating Level 5 [Member] | Moody's, Baa3 Rating [Member] | Libor Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.70%
Credit Rating Level 5 [Member] | Moody's, Baa3 Rating [Member] | Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.70%

6. Debt ACC3 Term Loan (Details

6. Debt ACC3 Term Loan (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Debt Instrument [Line Items]
Mortgage notes payable	$ 114,075	$ 113,667
AccThreeTermLoan [Member]
Debt Instrument [Line Items]
Mortgage notes payable	$ 115,000
Debt Instrument, Maturity Date	Mar. 27, 2018
AccThreeTermLoan [Member] | Libor Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.55%
AccThreeTermLoan [Member] | Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.55%
AccThreeTermLoan [Member] | Maximum [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	60.00%
AccThreeTermLoan [Member] | Minimum [Member]
Debt Instrument [Line Items]
Fixed Charge Coverage Ratio	1.70
Tangible Net Worth Amount	$ 1,300,000
Percentage Of Equity Offerings And Interests In Operating Partnerships To Be Added To Tangible Net Worth Threshold	80.00%
Debt Service Coverage Ratio	1.50

6. Debt Unsecured Term Loan (De

6. Debt Unsecured Term Loan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Unsecured Term Loan	$ 249,172	$ 248,945
Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Unsecured Term Loan	$ 250,000
Debt Instrument, Maturity Date	Jul. 21, 2019
Unsecured Term Loan [Member] | Maximum [Member]
Debt Instrument [Line Items]
Unsecured Debt To Unencumbered Assets	60.00%
Ratio of Total Indebtedness To Gross Assets Value	60.00%
Unsecured Term Loan [Member] | Minimum [Member]
Debt Instrument [Line Items]
Income from Unencumbered Assets To Unsecured Debt	12.50%
Fixed Charge Coverage Ratio	1.70
Tangible Net Worth Amount	$ 1,300,000
Percentage Of Equity Offerings And Interests In Operating Partnerships To Be Added To Tangible Net Worth Threshold	80.00%

6. Debt Applicable Margin of 65

6. Debt Applicable Margin of Unsecured Term Loan (Details) - Unsecured Term Loan [Member]	12 Months Ended
	Dec. 31, 2015
Pricing Level 1 [Member] | Libor Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.50%
Pricing Level 1 [Member] | Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.50%
Pricing Level 2 [Member] | Libor Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.60%
Pricing Level 2 [Member] | Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.60%
Pricing Level 3 [Member] | Libor Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.75%
Pricing Level 3 [Member] | Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.75%
Pricing Level 4 [Member] | Libor Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.90%
Pricing Level 4 [Member] | Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.90%
Pricing Level 5 [Member] | Libor Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	2.10%
Pricing Level 5 [Member] | Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.10%
Maximum [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	60.00%
Maximum [Member] | Pricing Level 1 [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	35.00%
Maximum [Member] | Pricing Level 2 [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	40.00%
Maximum [Member] | Pricing Level 3 [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	45.00%
Maximum [Member] | Pricing Level 4 [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	52.50%
Minimum [Member] | Pricing Level 2 [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	35.00%
Minimum [Member] | Pricing Level 3 [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	40.00%
Minimum [Member] | Pricing Level 4 [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	45.00%
Minimum [Member] | Pricing Level 5 [Member]
Debt Instrument [Line Items]
Ratio of Total Indebtedness To Gross Assets Value	52.50%

6. Debt Credit Rating for Uns66

6. Debt Credit Rating for Unsecured Term Loan (Details) - Unsecured Term Loan [Member]	12 Months Ended
	Dec. 31, 2015
Credit Rating Level 1 [Member] | Moody's, A3 Rating [Member] | Libor Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.825%
Credit Rating Level 1 [Member] | Moody's, A3 Rating [Member] | Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.00%
Credit Rating Level 2 [Member] | Moody's, Baa1 Rating [Member] | Libor Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.875%
Credit Rating Level 2 [Member] | Moody's, Baa1 Rating [Member] | Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.00%
Credit Rating Level 3 [Member] | Moody's, Baa2 Rating [Member] | Libor Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.00%
Credit Rating Level 3 [Member] | Moody's, Baa2 Rating [Member] | Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.00%
Credit Rating Level 4 [Member] | Moody's, Baa3 Rating [Member] | Libor Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.25%
Credit Rating Level 4 [Member] | Moody's, Baa3 Rating [Member] | Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.25%
Credit Rating Level 5 [Member] | Moody's, Baa3 Rating [Member] | Libor Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	1.65%
Unsecured Term Loan [Member] | Credit Rating Level 5 [Member] | Moody's, Baa3 Rating [Member] | Base Rate Loans [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.65%

6. Debt Unsecured Notes due 202

6. Debt Unsecured Notes due 2021 (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Unsecured notes payable	$ 834,963	$ 588,767
Unsecured Notes due 2021 [Member]
Debt Instrument [Line Items]
Debt Instrument, Issuance Date	Sep. 24, 2013
Unsecured notes payable	$ 600,000
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate	5.875%
Debt Instrument, Maturity Date	Sep. 15, 2021
Unencumbered Assets to Unsecured Debt	150.00%
Unsecured Notes due 2021 [Member] | Debt Instrument, Redemption, Period One [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage	100.00%
Unsecured Notes due 2021 [Member] | Debt Instrument, Redemption, Period Two [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage	104.406%
Unsecured Notes due 2021 [Member] | Debt Instrument, Redemption, Period Three [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage	102.938%
Unsecured Notes due 2021 [Member] | Debt Instrument, Redemption, Period Four [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage	101.469%
Unsecured Notes due 2021 [Member] | Debt Instrument, Redemption, Period Five [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage	100.00%
Unsecured Notes due 2021 [Member] | Change in Control [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage	101.00%
Unsecured Notes due 2021 [Member] | Asset Sales [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage	100.00%

6. Debt Unsecured Notes due 268

6. Debt Unsecured Notes due 2023 (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Unsecured notes payable	$ 834,963	$ 588,767
Unsecured Notes due 2023 [Member]
Debt Instrument [Line Items]
Debt Instrument, Issuance Date	Jun. 9, 2015
Unsecured notes payable	$ 250,000
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate	5.625%
Public offering price per note	99.205%
Debt Instrument, Maturity Date	Jun. 15, 2023
Unencumbered Assets to Unsecured Debt	150.00%
Unsecured Notes due 2023 [Member] | Debt Instrument, Redemption, Period One [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage	100.00%
Unsecured Notes due 2023 [Member] | Debt Instrument, Redemption, Period Two [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage	104.219%
Unsecured Notes due 2023 [Member] | Debt Instrument, Redemption, Period Three [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage	102.813%
Unsecured Notes due 2023 [Member] | Debt Instrument, Redemption, Period Four [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage	101.406%
Unsecured Notes due 2023 [Member] | Debt Instrument, Redemption, Period Five [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage	100.00%
Unsecured Notes due 2023 [Member] | Change in Control [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage	101.00%
Unsecured Notes due 2023 [Member] | Asset Sales [Member]
Debt Instrument [Line Items]
Debt Instrument, Redemption Price, Percentage	100.00%

6. Debt Maturity Summary (Detai

6. Debt Maturity Summary (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Long-term Debt	$ 1,215,000	$ 1,025,000
Total Debt in Percentage	100.00%
Debt, Weighted Average Interest Rate	4.60%
2016 [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	$ 3,750
Percentage of Total Debt	0.30%
Debt, Weighted Average Interest Rate	2.00%
2017 [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	$ 8,750
Percentage of Total Debt	0.70%
Debt, Weighted Average Interest Rate	2.00%
2018 [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	$ 102,500
Percentage of Total Debt	8.40%
Debt, Weighted Average Interest Rate	2.00%
2019 [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	$ 250,000
Percentage of Total Debt	20.60%
Debt, Weighted Average Interest Rate	1.70%
2020 [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	$ 0
Percentage of Total Debt	0.00%
Debt, Weighted Average Interest Rate	0.00%
2021 [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	$ 600,000
Percentage of Total Debt	49.40%
Debt, Weighted Average Interest Rate	5.90%
2022 [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	$ 0
Percentage of Total Debt	0.00%
Debt, Weighted Average Interest Rate	0.00%
2023 [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	$ 250,000
Percentage of Total Debt	20.60%
Debt, Weighted Average Interest Rate	5.60%
AccThreeTermLoan [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date	Mar. 27, 2018
AccThreeTermLoan [Member] | BeginningAprilOneTwoThousandSixteen [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	$ 1,250
Debt Instrument, Date of First Required Payment	Apr. 1, 2016
AccThreeTermLoan [Member] | BeginningAprilOneTwoThousandSeventeen [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	$ 2,500
Debt Instrument, Date of Increased Required Payment	Apr. 1, 2017
Unsecured Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument, Maturity Date	Jul. 21, 2019
Unsecured Notes due 2021 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate	5.875%
Debt Instrument, Maturity Date	Sep. 15, 2021
Unsecured Notes due 2023 [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate	5.625%
Debt Instrument, Maturity Date	Jun. 15, 2023
Debt Instrument, Unamortized Discount	$ 1,900
Fixed Rate Debt [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Fixed Interest, Amount	$ 850,000	600,000
Percentage of Total Debt	70.00%
Long-term Debt, Percentage Bearing Fixed Interest, Percentage Rate	5.80%
Fixed Rate Debt [Member] | 2016 [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	$ 0
Fixed Rate Debt [Member] | 2017 [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	0
Fixed Rate Debt [Member] | 2018 [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	0
Fixed Rate Debt [Member] | 2019 [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	0
Fixed Rate Debt [Member] | 2020 [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	0
Fixed Rate Debt [Member] | 2021 [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	600,000
Fixed Rate Debt [Member] | 2022 [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	0
Fixed Rate Debt [Member] | 2023 [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	250,000
Floating Rate Debt [Member]
Debt Instrument [Line Items]
Long-term Debt, Percentage Bearing Variable Interest, Amount	$ 365,000	$ 425,000
Percentage of Total Debt	30.00%
Floating Rate Debt [Member] | 2016 [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	$ 3,750
Floating Rate Debt [Member] | 2017 [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	8,750
Floating Rate Debt [Member] | 2018 [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	102,500
Floating Rate Debt [Member] | 2019 [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	250,000
Floating Rate Debt [Member] | 2020 [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	0
Floating Rate Debt [Member] | 2021 [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	0
Floating Rate Debt [Member] | 2022 [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	0
Floating Rate Debt [Member] | 2023 [Member]
Debt Instrument [Line Items]
Debt Instrument, Periodic Payment, Principal	$ 0

7. Related Party Transactions70

7. Related Party Transactions (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Feb. 02, 2016USD ($)a
Related Party Transaction [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party	$ 0	$ 0.1	$ 0.3
Aircraft Charter In lieu of salary	0	0	0.1
Related Party Transaction Rental Expenses From Transactions With Related Party	$ 0.4	$ 0.4	$ 0.4
Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest	81.40%
Adjacent to Ashburn Corporate Center [Member] | Board of Directors Chairman [Member]
Related Party Transaction [Line Items]
Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest	7.00%
Adjacent to Ashburn Corporate Center [Member] | Board of Directors Former Vice-Chairman [Member]
Related Party Transaction [Line Items]
Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest	1.00%
Part of Ashburn Corporate Center [Member] | Board of Directors Chairman [Member]
Related Party Transaction [Line Items]
Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest	23.00%
Part of Ashburn Corporate Center [Member] | Board of Directors Former Vice-Chairman [Member]
Related Party Transaction [Line Items]
Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest	18.00%
Part of Ashburn Corporate Center [Member] | Director [Member]
Related Party Transaction [Line Items]
Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest	4.00%
Subsequent Event [Member] | Adjacent to Ashburn Corporate Center [Member]
Related Party Transaction [Line Items]
Purchase Of Undeveloped Parcel Of Land In Acres | a				35.4
Purchase Price of Undeveloped Land Parcel				$ 15.6
Subsequent Event [Member] | Part of Ashburn Corporate Center [Member]
Related Party Transaction [Line Items]
Purchase Of Undeveloped Parcel Of Land In Acres | a				8.6
Purchase Price of Undeveloped Land Parcel				$ 4.6

8. Commitments and Contingenc71

8. Commitments and Contingencies (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
Long-term Purchase Commitment [Line Items]
Percentage Of Built In Gain That Can Be Recognized Without Triggering Tax Protection Provisions	90.00%
Initial Built In Gain	$ 667
Amount of Built In Gain That Can Be Recognized Without Triggering Tax Protection Provisions	$ 600
Increase in Percentage of Built In Gain That Can Be Recognized Each Year Without Triggering Tax Protection Provisions	10.00%
Percentage Of Built In Gain That Can Be Recognized In Two Thousand Seventeen Without Triggering Tax Protection Provisions	100.00%
Built in Gain Amount Tax Protected, No Guarantee on Secured Loan	$ 97
Percentage of Disinterested Members of Board for Approving Sales Resulting in Payments to Executives or Directors	75.00%
ACC7 Phase II [Member]
Long-term Purchase Commitment [Line Items]
Estimated Control Cost	$ 43.1
Amount of Control Estimate Incurred	40.7
Total Commitments For Purchase of Equipment And Labor Related to Development	1.1
ACC7 Phase III [Member]
Long-term Purchase Commitment [Line Items]
Estimated Control Cost	75
Amount of Control Estimate Incurred	53.4
Total Commitments For Purchase of Equipment And Labor Related to Development	10.5
CH2 Phase II [Member]
Long-term Purchase Commitment [Line Items]
Estimated Control Cost	17.8
Amount of Control Estimate Incurred	10.6
Total Commitments For Purchase of Equipment And Labor Related to Development	3.7
CH2 Phase III [Member]
Long-term Purchase Commitment [Line Items]
Estimated Control Cost	66.6
Amount of Control Estimate Incurred	15.1
Total Commitments For Purchase of Equipment And Labor Related to Development	$ 18.8

9. Redeemable noncontrolling 72

9. Redeemable noncontrolling interests operating partnership / Redeemable partnership units (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Redeemable noncontrolling interests – operating partnership / Redeemable partnership units [Line Items]
Redeemable noncontrolling interests - operating partnership	$ 479,189	$ 513,134	$ 387,244	$ 453,889
Share Price	$ 31.79	$ 33.24
Redemption of operating partnership units, shares	363,674	234,300	3,115,269

10. Preferred Stock Preferred S

10. Preferred Stock Preferred Stock Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Series A cumulative redeemable perpetual preferred stock [Member]
Preferred Stock [Line Items]
Preferred stock, shares issued	7,400,000	7,400,000
Preferred Stock, Dividend Rate, Percentage	7.875%
Preferred stock, $.001 par value, 50,000,000 shares authorized	$ 185,000	$ 185,000
Preferred Stock, Liquidation Preference Per Share	$ 25
Preferred Stock, Redemption Price Per Share	$ 25
Preferred Stock, Increased Dividend Rate, Percentage	11.875%
Preferred Stock Redemption Period After Change in Control	90 days
Series B cumulative redeemable perpetual preferred stock [Member]
Preferred Stock [Line Items]
Preferred stock, shares issued	6,650,000	6,650,000
Preferred Stock, Dividend Rate, Percentage	7.625%
Preferred stock, $.001 par value, 50,000,000 shares authorized	$ 166,250	$ 166,250
Preferred Stock, Liquidation Preference Per Share	$ 25
Preferred Stock, Redemption Price Per Share	$ 25
Preferred Stock Redemption Period After Change in Control	120 days
Share Cap to Determine Redemption Price in Change in Control	2.105

10. Preferred Stock Preferred74

10. Preferred Stock Preferred Stock Schedule of Preferred Stock Dividend (Details) - $ / shares	3 Months Ended												12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Series A Preferred Stock [Member]
Preferred Stock Dividend [Line Items]
Record Date	Dec. 30, 2015	Oct. 2, 2015	Jul. 2, 2015	Apr. 2, 2015	Dec. 30, 2014	Oct. 3, 2014	Jul. 3, 2014	Apr. 4, 2014	Dec. 27, 2013	Oct. 4, 2013	Jul. 5, 2013	Apr. 5, 2013
Payment Date	Jan. 15, 2016	Oct. 15, 2015	Jul. 15, 2015	Apr. 15, 2015	Jan. 15, 2015	Oct. 15, 2014	Jul. 15, 2014	Apr. 15, 2014	Jan. 15, 2014	Oct. 15, 2013	Jul. 15, 2013	Apr. 15, 2013
Cash Dividend	$ 0.4921875	$ 0.4921875	$ 0.4921875	$ 0.4921875	$ 0.4921875	$ 0.4921875	$ 0.4921875	$ 0.4921875	$ 0.4921875	$ 0.4921875	$ 0.4921875	$ 0.4921875	$ 1.9687500	$ 1.9687500	$ 1.9687500
Ordinary Taxable Dividend	0.4921875	0.4921875	0.4921875	0.4921875	0.4921875	0.4921875	0.4921875	0.4921875	0.4921875	0.4921875	0.4921875	0.4921875	1.9687500	1.9687500	1.9687500
Nontaxable Return of Capital Distributions	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	0	0	0
Series B Preferred Stock [Member]
Preferred Stock Dividend [Line Items]
Record Date	Dec. 30, 2015	Oct. 2, 2015	Jul. 2, 2015	Apr. 2, 2015	Dec. 30, 2014	Oct. 3, 2014	Jul. 3, 2014	Apr. 4, 2014	Dec. 27, 2013	Oct. 4, 2013	Jul. 5, 2013	Apr. 5, 2013
Payment Date	Jan. 15, 2016	Oct. 15, 2015	Jul. 15, 2015	Apr. 15, 2015	Jan. 15, 2015	Oct. 15, 2014	Jul. 15, 2014	Apr. 15, 2014	Jan. 15, 2014	Oct. 15, 2013	Jul. 15, 2013	Apr. 15, 2013
Cash Dividend	$ 0.4765625	$ 0.4765625	$ 0.4765625	$ 0.4765625	$ 0.4765625	$ 0.4765625	$ 0.4765625	$ 0.4765625	$ 0.4765625	$ 0.4765625	$ 0.4765625	$ 0.4765625	1.9062500	1.9062500	1.9062500
Ordinary Taxable Dividend	0.4765625	0.4765625	0.4765625	0.4765625	0.4765625	0.4765625	0.4765625	0.4765625	0.4765625	0.4765625	0.4765625	0.4765625	1.9062500	1.9062500	1.9062500
Nontaxable Return of Capital Distributions	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0

11. Stockholders Equity of th75

11. Stockholders Equity of the REIT and Partners Capital of the OP Stockholders Equity of the REIT and Partners Capital of the OP Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Stockholders’ Equity of the REIT and Partners’ Capital of the OP [Line Items]
Issuance of stock awards, shares													565,162	163,187	216,209
Redemption of operating partnership units, shares													363,674	234,300	3,115,269
Stock Repurchase Program, Authorized Amount	$ 120,000				$ 122,200								$ 120,000	$ 122,200
Common stock repurchase, shares													(1,002,610)	0	(1,632,673)
Common stock repurchases													$ 31,912		$ 37,792
Common Stock [Member]
Stockholders’ Equity of the REIT and Partners’ Capital of the OP [Line Items]
Cash Dividend	$ 0.47	$ 0.42	$ 0.42	$ 0.42	$ 0.42	$ 0.35	$ 0.35	$ 0.35	$ 0.25	$ 0.25	$ 0.25	$ 0.20	$ 1.73	$ 1.47	$ 0.95
Ordinary Taxable Dividend	$ 0.33	$ 0.42	$ 0.42	$ 0.42	$ 0.39	$ 0.35	$ 0.35	$ 0.35	$ 0	$ 0.214	$ 0.214	$ 0.172	1.59	$ 1.44	$ 0.600
January Two Zero One Six [Member] | Common Stock [Member]
Stockholders’ Equity of the REIT and Partners’ Capital of the OP [Line Items]
Ordinary Taxable Dividend													0.14
January Two Zero One Five [Member] | Common Stock [Member]
Stockholders’ Equity of the REIT and Partners’ Capital of the OP [Line Items]
Ordinary Taxable Dividend													0.03
January Two Zero One Four [Member] | Common Stock [Member]
Stockholders’ Equity of the REIT and Partners’ Capital of the OP [Line Items]
Ordinary Taxable Dividend													$ 0.25

11. Stockholders Equity of th76

11. Stockholders Equity of the REIT and Partners Capital of the OP Stockholders Equity of the REIT and Partners Capital of the OP Schedule of Common Stock Dividend (Details) - Common Stock [Member] - $ / shares	3 Months Ended												12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Class of Stock [Line Items]
Record Date	Dec. 30, 2015	Oct. 2, 2015	Jul. 2, 2015	Apr. 2, 2015	Dec. 30, 2014	Oct. 3, 2014	Jul. 3, 2014	Apr. 4, 2014	Dec. 27, 2013	Oct. 4, 2013	Jul. 5, 2013	Apr. 5, 2013
Payment Date	Jan. 16, 2016	Oct. 15, 2015	Jul. 15, 2015	Apr. 15, 2015	Jan. 15, 2015	Oct. 15, 2014	Jul. 15, 2014	Apr. 15, 2014	Jan. 15, 2014	Oct. 15, 2013	Jul. 15, 2013	Apr. 15, 2013
Cash Dividend	$ 0.47	$ 0.42	$ 0.42	$ 0.42	$ 0.42	$ 0.35	$ 0.35	$ 0.35	$ 0.25	$ 0.25	$ 0.25	$ 0.20	$ 1.73	$ 1.47	$ 0.95
Ordinary Taxable Dividend	0.33	0.42	0.42	0.42	0.39	0.35	0.35	0.35	0	0.214	0.214	0.172	1.59	1.44	0.600
Nontaxable Return of Capital Distributions	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0.036	$ 0.036	$ 0.028	$ 0	$ 0	$ 0.100

12. Equity Compensation Plan Na

12. Equity Compensation Plan Narrative (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)$ / sharesshares	Dec. 31, 2014USD ($)$ / sharesshares	Dec. 31, 2013USD ($)$ / sharesshares	Dec. 31, 2012shares
Equity Compensation Plan [Line Items]
Maximum Number of Share Equivalents Authorized	6,300,000
Share equivalent ratio, other than stock options and SARs	2.36
Cumulative Share Equivalents Issued From The Plan	3,247,727
Share Equivalents Remaining Available	3,052,273
Shares of restricted stock, Granted	171,475	149,608	203,241
Value of Restricted Stock Awarded during period | $	$ 5.5	$ 3.8	$ 4.6
Shares of restricted stock, Vested	138,585	125,798	162,353
Value of Restricted Stock on Vesting Date | $	$ 4.3	$ 3.4	$ 3.8
Unearned Compensation on Restricted Stock | $	$ 6.2
Weighted Average Vesting Period	1 year
Granted	0	0	374,214
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercised, Intrinsic Value | $	$ 3.7	$ 7.7	$ 4.5
Performance units, forfeited	7,737	3,785	34,843
Weighted Average Fair Value, performance units forfeited | $ / shares	$ 28.71	$ 23.98	$ 22.86
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	349,142	323,989	303,964	297,919
Stock Options [Member]
Equity Compensation Plan [Line Items]
Weighted Average Vesting Period	73 days	183 days	292 days
Performance Shares [Member]
Equity Compensation Plan [Line Items]
Unearned Compensation on Restricted Stock | $	$ 1.8
Performance units, forfeited	4,225	0	22,091
Weighted Average Fair Value, performance units forfeited | $ / shares	$ 36.30		$ 26.93
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number	32,985	0
Minimum [Member]
Equity Compensation Plan [Line Items]
Potential Number Of Shares Issued At Vesting Of Performance Units	0.00%
Maximum [Member]
Equity Compensation Plan [Line Items]
Potential Number Of Shares Issued At Vesting Of Performance Units	300.00%

12. Equity Compensation Plan Su

12. Equity Compensation Plan Summary of Restricted Stock (Details) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Equity Compensation Plan [Line Items]
Shares of restricted stock, Unvested balance at beginning balance	323,989	303,964	297,919
Shares of restricted stock, Granted	171,475	149,608	203,241
Shares of restricted stock, Vested	(138,585)	(125,798)	(162,353)
Shares of restricted stock, Forfeited	(7,737)	(3,785)	(34,843)
Shares of restricted stock, Unvested balance at ending balance	349,142	323,989	303,964
Weighted Average Grant Date Fair Value, Unvested balance at beginning balance	$ 24.10	$ 22.89	$ 22.31
Weighted Average Grant Date Fair Value, Granted	32.12	25.63	22.82
Weighted Average Grant Date Fair Value, Vested	23.87	23.02	21.73
Weighted Average Grant Date Fair Value, Forfeited	28.71	23.98	22.86
Weighted Average Grant Date Fair Value, Unvested balance at ending balance	$ 28.02	$ 24.10	$ 22.89

12. Equity Compensation Plan 79

12. Equity Compensation Plan Summary of Stock Options (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Equity Compensation Plan [Line Items]
Under option, beginning balance	1,592,854	2,099,910	2,076,781
Granted	0	0	374,214
Exercised	(362,642)	(507,056)	(250,472)
Forfeited	0	0	(100,613)
Under option, ending balance	1,230,212	1,592,854	2,099,910
Weighted Average Exercise Price, Under Option, Beginning balance	$ 19.09	$ 17.13	$ 15.17
Weighted Average Exercise Price, Granted	0	0	22.62
Weighted Average Exercise Price, Exercised	21.87	10.95	6.83
Weighted Average Exercise Price, Forfeited	0	0	22.83
Weighted Average Exercise Price, Under Option, Ending balance	$ 18.28	$ 19.09	$ 17.13
Total Unearned Compensation	$ 0.1	$ 0.7	$ 1.9
Weighted Average Vesting Period	1 year
Weighted Average Remaining Contractual Term	4 years 329 days	6 years 73 days	6 years 329 days
Stock Options [Member]
Equity Compensation Plan [Line Items]
Weighted Average Vesting Period	73 days	183 days	292 days

12. Equity Compensation Plan 80

12. Equity Compensation Plan Summary of Unvested Stock Options (Details) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Equity Compensation Plan [Line Items]
Unvested balance, beginning balance	302,324	684,111	809,991
Granted	0	0	374,214
Vested	(263,553)	(381,787)	(399,481)
Forfeited	0	0	(100,613)
Unvested balance, ending balance	38,771	302,324	684,111
Weighted Average Grant Date Fair Value, Unvested at beginning balance	$ 5.05	$ 5.73	$ 6.96
Weighted Average Grant Date Fair Value, Granted	$ 0	$ 0	$ 4.75
Weighted Average Grant Date Fair Value, Vested	5.10	6.28	7.34
Weighted Average Grant Date Fair Value, Forfeited	$ 0	$ 0	$ 5.55
Weighted Average Grant Date Fair Value, Unvested at ending balance	$ 4.75	$ 5.05	$ 5.73

12. Equity Compensation Plan 81

12. Equity Compensation Plan Summary of Exercisable Stock Options (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Equity Compensation Plan [Line Items]
Options Exercisable, beginning balance	1,290,530	1,415,799	1,266,790
Vested	263,553	381,787	399,481
Exercised	(362,642)	(507,056)	(250,472)
Options Exercisable, ending balance	1,191,441	1,290,530	1,415,799
Weighted Average Grant Date Fair Value, Exercisable at beginning balance	$ 5.74	$ 4.81	$ 3.52
Weighted Average Grant Date Fair Value, Vested	5.10	6.28	7.34
Weighted Average Grant Date Fair Value, Exercised	6.34	3.54	2.35
Weighted Average Grant Date Fair Value, Exercisable at ending balance	$ 5.41	$ 5.74	$ 4.81
Intrinsic Value	$ 16.3	$ 19.3	$ 14.7
Weighted Average Exercise Price	$ 18.14	$ 18.27	$ 14.33
Weighted Average Remaining Contractual Term	4 years 329 days	5 years 292 days	6 years 37 days

12. Equity Compensation Plan 82

12. Equity Compensation Plan Summary of Assumptions for Stock Options Granted (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Equity Compensation Plan [Line Items]
Number of Options Granted	0	0	374,214
Exercise Price	$ 0	$ 0	$ 22.62
Expected term (years)			5 years
Expected volatility			34.00%
Expected annual dividend			4.00%
Risk-free rate			0.83%
Total grant fair value at date of grant (millions)			$ 1.8

12. Equity Compensation Plan 83

12. Equity Compensation Plan Summary of Assumptions Used for Performance Units Granted (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Equity Compensation Plan [Line Items]
Expected volatility			34.00%
Expected annual dividend			4.00%
Risk-free rate			0.83%
Total grant fair value at date of grant (millions)			$ 1.8
Performance Shares [Member]
Equity Compensation Plan [Line Items]
Performance Units Granted In Period	48,674	110,441	60,468
Expected volatility	24.00%	30.00%	33.00%
Expected annual dividend	5.00%	5.00%	4.00%
Risk-free rate	1.06%	0.74%	0.40%
Performance unit fair value at date of grant	$ 38.34	$ 33.50	$ 25.59
Total grant fair value at date of grant (millions)	$ 1.9	$ 3.7	$ 1.5
Maximum value of grant on vesting date based on closing price of the Company's stock at the date of grant	$ 4.7	$ 8.5	$ 4.1

13. Earnings Per Share of the84

13. Earnings Per Share of the REIT (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015		Mar. 31, 2015		Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings per share of the REIT [Line Items]
Weighted average common shares – basic																	65,184,013	65,486,108	64,645,316
Effect of dilutive securities																	0	600,271	828,723
Weighted average common shares – diluted																	65,184,013	66,086,379	65,474,039
Net income attributable to common shares	$ (79,871)		$ 19,062		$ 19,668		$ 15,803		$ 18,536		$ 18,960		$ 21,121		$ 20,045		$ (25,338)	$ 78,662	$ 21,146
Net income allocated to unvested restricted shares																	(599)	(484)	(267)
Net income attributable to common shares, adjusted																	$ (25,937)	$ 78,178	$ 20,879
Earnings per common share – basic	$ (1.23)		$ 0.29		$ 0.30		$ 0.24		$ 0.28	[1]	$ 0.29	[1]	$ 0.32	[1]	$ 0.30	[1]	$ (0.40)	$ 1.19	$ 0.32
Net income attributable to common shares																	$ (25,937)	$ 78,178	$ 21,146
Adjustments to redeemable noncontrolling interests																	0	0	55
Adjusted net income available to common shares																	$ (25,937)	$ 78,178	$ 21,201
Earnings per common share – diluted	$ (1.23)	[1]	$ 0.29	[1]	$ 0.30	[1]	$ 0.24	[1]	$ 0.28		$ 0.29		$ 0.32		$ 0.30		$ (0.40)	$ 1.18	$ 0.32
Equity Option [Member]
Earnings per share of the REIT [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount																	600,000	0	600,000
Performance Shares [Member]
Earnings per share of the REIT [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount																	100,000	100,000	100,000
[1]	Amounts do not equal full year results due to rounding.

14. Earnings Per Unit of the 85

14. Earnings Per Unit of the Operating Partnership (Details) - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Earnings per unit of the Operating Partnership [Line Items]
Weighted average common units – basic (includes redeemable partnership units and units of general and limited partners)	80,599,199	81,053,127	80,580,556
Effect of dilutive securities	0	600,271	828,723
Weighted average common units – diluted	80,599,199	81,653,398	81,409,279
Equity Option [Member]
Earnings per unit of the Operating Partnership [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	600,000	0	600,000
Performance Shares [Member]
Earnings per unit of the Operating Partnership [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	100,000	100,000	100,000

15. Employee Benefit Plan (Deta

15. Employee Benefit Plan (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee Benefit Plan [Abstract]
Percentage Of Employees Contribution Contributed By Employer	50.00%
Percentage Of Employee's Salary Contributed By Employer	4.00%
Defined Benefit Plan, Contributions by Employer	$ 0.5	$ 0.4	$ 0.4

16. Fair Value (Details)

16. Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair Value Disclosures [Abstract]
Long-term debt, net of discount	$ 1,213,100
Long-term Debt	1,215,000	$ 1,025,000
Long-term Debt, Fair Value	$ 1,237,200	$ 1,037,800

17. Quarterly Financial Infor88

17. Quarterly Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2015		Sep. 30, 2015		Jun. 30, 2015		Mar. 31, 2015		Dec. 31, 2014		Sep. 30, 2014		Jun. 30, 2014		Mar. 31, 2014		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 115,923		$ 115,337		$ 113,826		$ 107,314		$ 107,977		$ 105,578		$ 101,950		$ 102,087		$ 452,400	$ 417,592	$ 375,109
Net (loss) income	(91,953)		30,393		31,141		26,333		29,737		30,272		32,958		31,644		(4,086)	124,611	53,605
Net income attributable to common shares	$ (79,871)		$ 19,062		$ 19,668		$ 15,803		$ 18,536		$ 18,960		$ 21,121		$ 20,045		$ (25,338)	$ 78,662	$ 21,146
Net income attributable to common shares	$ (1.23)		$ 0.29		$ 0.30		$ 0.24		$ 0.28	[1]	$ 0.29	[1]	$ 0.32	[1]	$ 0.30	[1]	$ (0.40)	$ 1.19	$ 0.32
Net income attributable to common shares	$ (1.23)	[1]	$ 0.29	[1]	$ 0.30	[1]	$ 0.24	[1]	$ 0.28		$ 0.29		$ 0.32		$ 0.30		$ (0.40)	$ 1.18	$ 0.32
[1]	Amounts do not equal full year results due to rounding.

18. Supplemental Consolidatin89

18. Supplemental Consolidating Financial Data for Subsidiary Guarantors of the Unsecured Notes Supplemental Consolidating Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2015		Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Supplemental Consolidating Statements Of Balance Sheets [Line Items]
Land	$ 94,203		$ 83,793
Buildings and improvements	2,736,936		2,623,539
Income producing property	2,831,139		2,707,332
Less: accumulated depreciation	(560,837)		(504,869)
Net income producing property	2,270,302		2,202,463
Construction in progress and land held for development	300,939	[1]	358,965
Net real estate	2,571,241		2,561,428
Cash and cash equivalents	31,230		29,598	$ 38,733	$ 23,578
Rents and other receivables	9,588		8,113
Deferred rent, net	128,941		142,365
Lease contracts above market value, net	6,029		8,054
Deferred costs, net	23,774		24,874
Prepaid expenses and other assets	44,689		48,295
Total assets	2,815,492		2,822,727
Line of credit	0		60,000
Mortgage notes payable	114,075		113,667
Unsecured Term Loan	249,172		248,945
Unsecured notes payable	834,963		588,767
Accounts payable and accrued liabilities	32,301		26,973
Construction costs payable	22,043		32,949
Accrued interest payable	11,821		10,759
Distribution payable	43,906		39,981
Lease contracts below market value, net	4,132		7,037
Prepaid rents and other liabilities	67,477		65,174
Total liabilities	1,379,890		1,194,252
Commitments and contingencies	0		0
Total liabilities and stockholders’ equity	2,815,492		2,822,727
Subsidiaries [Member]
Supplemental Consolidating Statements Of Balance Sheets [Line Items]
Land	94,203		83,793
Buildings and improvements	2,736,936		2,623,539
Income producing property	2,831,139		2,707,332
Less: accumulated depreciation	(560,837)		(504,869)
Net income producing property	2,270,302		2,202,463
Construction in progress and land held for development	300,939		358,965
Net real estate	2,571,241		2,561,428
Cash and cash equivalents	27,015		25,380	34,514	19,282
Rents and other receivables	9,588		8,113
Deferred rent, net	128,941		142,365
Lease contracts above market value, net	6,029		8,054
Deferred costs, net	23,774		24,874
Investment in affiliates	0		0
Prepaid expenses and other assets	44,689		48,295
Total assets	2,811,277		2,818,509
Line of credit	0		60,000
Mortgage notes payable	114,075		113,667
Unsecured Term Loan	249,172		248,945
Unsecured notes payable	834,963		588,767
Accounts payable and accrued liabilities	32,301		26,973
Construction costs payable	22,043		32,949
Accrued interest payable	11,821		10,759
Distribution payable	43,906		39,981
Lease contracts below market value, net	4,132		7,037
Prepaid rents and other liabilities	67,477		65,174
Total liabilities	1,379,890		1,194,252
Redeemable partnership units	479,189		513,134
Commitments and contingencies	0		0
General Partners' Capital	6,021		7,619
Total partners’ capital	952,198		1,111,123	1,248,055	1,262,136
Total liabilities and stockholders’ equity	2,811,277		2,818,509
Subsidiaries [Member] | Operating Partnership [Member]
Supplemental Consolidating Statements Of Balance Sheets [Line Items]
Land	0		0
Buildings and improvements	0		0
Income producing property	0		0
Less: accumulated depreciation	0		0
Net income producing property	0		0
Construction in progress and land held for development	0		0
Net real estate	0		0
Cash and cash equivalents	21,697		21,806	32,903	18,240
Rents and other receivables	1,391		1,775
Deferred rent, net	0		0
Lease contracts above market value, net	0		0
Deferred costs, net	3,236		3,669
Investment in affiliates	2,546,465		2,547,049
Prepaid expenses and other assets	3,025		2,865
Total assets	2,575,814		2,577,164
Line of credit	0		60,000
Mortgage notes payable	0		0
Unsecured Term Loan	249,172		248,945
Unsecured notes payable	834,963		588,767
Accounts payable and accrued liabilities	4,516		4,432
Construction costs payable	43		0
Accrued interest payable	11,815		10,754
Distribution payable	43,906		39,981
Lease contracts below market value, net	0		0
Prepaid rents and other liabilities	12		28
Total liabilities	1,144,427		952,907
Redeemable partnership units	479,189		513,134
Commitments and contingencies	0		0
General Partners' Capital	6,021		7,619
Total partners’ capital	952,198		1,111,123
Total liabilities and stockholders’ equity	2,575,814		2,577,164
Subsidiaries [Member] | Subsidiary Guarantors [Member]
Supplemental Consolidating Statements Of Balance Sheets [Line Items]
Land	84,258		79,935
Buildings and improvements	2,399,016		2,427,706
Income producing property	2,483,274		2,507,641
Less: accumulated depreciation	(522,096)		(473,203)
Net income producing property	1,961,178		2,034,438
Construction in progress and land held for development	25,545		145,229
Net real estate	1,986,723		2,179,667
Cash and cash equivalents	0		0	0	361
Rents and other receivables	7,563		5,513
Deferred rent, net	122,830		139,542
Lease contracts above market value, net	6,029		8,054
Deferred costs, net	14,250		16,098
Investment in affiliates	0		0
Prepaid expenses and other assets	39,642		43,866
Total assets	2,177,037		2,392,740
Line of credit	0		0
Mortgage notes payable	0		0
Unsecured Term Loan	0		0
Unsecured notes payable	0		0
Accounts payable and accrued liabilities	23,615		19,580
Construction costs payable	293		4,312
Accrued interest payable	0		0
Distribution payable	0		0
Lease contracts below market value, net	4,132		7,037
Prepaid rents and other liabilities	62,630		61,728
Total liabilities	90,670		92,657
Redeemable partnership units	0		0
Commitments and contingencies	0		0
General Partners' Capital	0		0
Total partners’ capital	2,086,367		2,300,083
Total liabilities and stockholders’ equity	2,177,037		2,392,740
Subsidiaries [Member] | Subsidiary Non-Guarantors [Member]
Supplemental Consolidating Statements Of Balance Sheets [Line Items]
Land	9,945		3,858
Buildings and improvements	337,920		195,833
Income producing property	347,865		199,691
Less: accumulated depreciation	(38,741)		(31,666)
Net income producing property	309,124		168,025
Construction in progress and land held for development	275,394		213,736
Net real estate	584,518		381,761
Cash and cash equivalents	5,318		3,574	1,611	681
Rents and other receivables	634		825
Deferred rent, net	6,111		2,823
Lease contracts above market value, net	0		0
Deferred costs, net	6,288		5,107
Investment in affiliates	0		0
Prepaid expenses and other assets	2,022		1,564
Total assets	604,891		395,654
Line of credit	0		0
Mortgage notes payable	114,075		113,667
Unsecured Term Loan	0		0
Unsecured notes payable	0		0
Accounts payable and accrued liabilities	4,170		2,961
Construction costs payable	21,707		28,637
Accrued interest payable	6		5
Distribution payable	0		0
Lease contracts below market value, net	0		0
Prepaid rents and other liabilities	4,835		3,418
Total liabilities	144,793		148,688
Redeemable partnership units	0		0
Commitments and contingencies	0		0
General Partners' Capital	0		0
Total partners’ capital	460,098		246,966
Total liabilities and stockholders’ equity	604,891		395,654
Subsidiaries [Member] | Eliminations [Member]
Supplemental Consolidating Statements Of Balance Sheets [Line Items]
Land	0		0
Buildings and improvements	0		0
Income producing property	0		0
Less: accumulated depreciation	0		0
Net income producing property	0		0
Construction in progress and land held for development	0		0
Net real estate	0		0
Cash and cash equivalents	0		0	$ 0	$ 0
Rents and other receivables	0		0
Deferred rent, net	0		0
Lease contracts above market value, net	0		0
Deferred costs, net	0		0
Investment in affiliates	(2,546,465)		(2,547,049)
Prepaid expenses and other assets	0		0
Total assets	(2,546,465)		(2,547,049)
Line of credit	0		0
Mortgage notes payable	0		0
Unsecured Term Loan	0		0
Unsecured notes payable	0		0
Accounts payable and accrued liabilities	0		0
Construction costs payable	0		0
Accrued interest payable	0		0
Distribution payable	0		0
Lease contracts below market value, net	0		0
Prepaid rents and other liabilities	0		0
Total liabilities	0		0
Redeemable partnership units	0		0
Commitments and contingencies	0		0
General Partners' Capital	0		0
Total partners’ capital	(2,546,465)		(2,547,049)
Total liabilities and stockholders’ equity	(2,546,465)		(2,547,049)
Subsidiaries [Member] | Series A Preferred Stock [Member]
Supplemental Consolidating Statements Of Balance Sheets [Line Items]
Limited Partners' Capital	185,000		185,000
Subsidiaries [Member] | Series A Preferred Stock [Member] | Operating Partnership [Member]
Supplemental Consolidating Statements Of Balance Sheets [Line Items]
Limited Partners' Capital	185,000		185,000
Subsidiaries [Member] | Series A Preferred Stock [Member] | Subsidiary Guarantors [Member]
Supplemental Consolidating Statements Of Balance Sheets [Line Items]
Limited Partners' Capital	0		0
Subsidiaries [Member] | Series A Preferred Stock [Member] | Subsidiary Non-Guarantors [Member]
Supplemental Consolidating Statements Of Balance Sheets [Line Items]
Limited Partners' Capital	0		0
Subsidiaries [Member] | Series A Preferred Stock [Member] | Eliminations [Member]
Supplemental Consolidating Statements Of Balance Sheets [Line Items]
Limited Partners' Capital	0		0
Subsidiaries [Member] | Series B Preferred Stock [Member]
Supplemental Consolidating Statements Of Balance Sheets [Line Items]
Limited Partners' Capital	166,250		166,250
Subsidiaries [Member] | Series B Preferred Stock [Member] | Operating Partnership [Member]
Supplemental Consolidating Statements Of Balance Sheets [Line Items]
Limited Partners' Capital	166,250		166,250
Subsidiaries [Member] | Series B Preferred Stock [Member] | Subsidiary Guarantors [Member]
Supplemental Consolidating Statements Of Balance Sheets [Line Items]
Limited Partners' Capital	0		0
Subsidiaries [Member] | Series B Preferred Stock [Member] | Subsidiary Non-Guarantors [Member]
Supplemental Consolidating Statements Of Balance Sheets [Line Items]
Limited Partners' Capital	0		0
Subsidiaries [Member] | Series B Preferred Stock [Member] | Eliminations [Member]
Supplemental Consolidating Statements Of Balance Sheets [Line Items]
Limited Partners' Capital	0		0
Subsidiaries [Member] | Limited partners' common units [Member]
Supplemental Consolidating Statements Of Balance Sheets [Line Items]
Limited Partners' Capital	594,927		752,254
Subsidiaries [Member] | Limited partners' common units [Member] | Operating Partnership [Member]
Supplemental Consolidating Statements Of Balance Sheets [Line Items]
Limited Partners' Capital	594,927		752,254
Subsidiaries [Member] | Limited partners' common units [Member] | Subsidiary Guarantors [Member]
Supplemental Consolidating Statements Of Balance Sheets [Line Items]
Limited Partners' Capital	2,086,367		2,300,083
Subsidiaries [Member] | Limited partners' common units [Member] | Subsidiary Non-Guarantors [Member]
Supplemental Consolidating Statements Of Balance Sheets [Line Items]
Limited Partners' Capital	460,098		246,966
Subsidiaries [Member] | Limited partners' common units [Member] | Eliminations [Member]
Supplemental Consolidating Statements Of Balance Sheets [Line Items]
Limited Partners' Capital	$ (2,546,465)		$ (2,547,049)
[1]	(1)Properties located in Ashburn, VA (ACC7 Phases III-IV and ACC8); Piscataway, NJ (NJ1 Phase II), Elk Grove Village, IL (CH2 Phases II-III and CH3) and Santa Clara, CA (SC2). In the fourth quarter of 2015, we determined that it was more likely than not that we would sell our NJ1 data center prior to the end of its previously estimated useful life. We believe that it is unlikely that we will develop NJ1 Phase II prior to the sale.In August 2015, we acquired two parcels of land totaling 9.7 acres for a total purchase price of $8.6 million. These parcels are adjacent to our CH1 data center in Elk Grove Village, Illinois and are being held for the future development of CH3. In February 2016, we acquired two parcels of undeveloped land in Ashburn, Virginia. One parcel is a 35.4 acre site that we purchased for $15.6 million, and the other parcel is an 8.6 acre site that we purchased for $4.6 million. These parcels are being held for future development of ACC9, ACC10 and either a powered base shell or build-to-suit data center.

18. Supplemental Consolidatin90

18. Supplemental Consolidating Financial Data for Subsidiary Guarantors of the Unsecured Notes Supplemental Consolidating Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues:
Base rent									$ 298,585	$ 285,716	$ 265,695
Recoveries from tenants									139,537	124,853	104,271
Other revenues									14,278	7,023	5,143
Total revenues	$ 115,923	$ 115,337	$ 113,826	$ 107,314	$ 107,977	$ 105,578	$ 101,950	$ 102,087	452,400	417,592	375,109
Expenses:
Property operating costs									130,051	117,339	103,522
Real estate taxes and insurance									21,335	14,195	14,380
Depreciation and amortization									104,044	96,780	93,058
General and administrative									18,064	17,181	16,261
Impairment of Long-Lived Assets to be Disposed of									122,472	0	0
Other expenses									16,859	9,222	3,650
Total expenses									412,825	254,717	230,871
Operating income									39,575	162,875	144,238
Interest income									60	116	137
Interest:
Expense incurred									(40,570)	(33,699)	(46,443)
Amortization of deferred financing costs									(3,151)	(2,980)	(3,349)
Loss on early extinguishment of debt									0	(1,701)	(40,978)
Net (loss) income	$ (91,953)	$ 30,393	$ 31,141	$ 26,333	$ 29,737	$ 30,272	$ 32,958	$ 31,644	(4,086)	124,611	53,605
Preferred stock dividends									(27,245)	(27,245)	(27,245)
Subsidiaries [Member]
Revenues:
Base rent									298,585	285,716	265,695
Recoveries from tenants									139,537	124,853	104,271
Other revenues									14,278	7,023	5,143
Total revenues									452,400	417,592	375,109
Expenses:
Property operating costs									130,051	117,339	103,522
Real estate taxes and insurance									21,335	14,195	14,380
Depreciation and amortization									104,044	96,780	93,058
General and administrative									18,064	17,181	16,261
Impairment of Long-Lived Assets to be Disposed of									122,472	0	0
Other expenses									16,859	9,222	3,650
Total expenses									412,825	254,717	230,871
Operating income									39,575	162,875	144,238
Interest income									60	116	137
Interest:
Expense incurred									(40,570)	(33,699)	(46,443)
Amortization of deferred financing costs									(3,151)	(2,980)	(3,349)
Loss on early extinguishment of debt									0	(1,701)	(40,978)
Equity in earnings									0	0	0
Net (loss) income									(4,086)	124,611	53,605
Preferred stock dividends									(27,245)	(27,245)	(27,245)
Net Income Loss Available To Common Unit holders Basic									(31,331)	97,366	26,360
Subsidiaries [Member] | Operating Partnership [Member]
Revenues:
Base rent									18,061	17,499	15,301
Recoveries from tenants									0	0	0
Other revenues									0	0	0
Total revenues									18,061	17,499	15,301
Expenses:
Property operating costs									0	0	198
Real estate taxes and insurance									0	0	0
Depreciation and amortization									43	63	81
General and administrative									17,574	16,159	15,605
Impairment of Long-Lived Assets to be Disposed of									0
Other expenses									6,151	3,508	778
Total expenses									23,768	19,730	16,662
Operating income									(5,707)	(2,231)	(1,361)
Interest income									60	115	(148)
Interest:
Expense incurred									(50,081)	(41,222)	(47,343)
Amortization of deferred financing costs									(3,454)	(3,173)	(3,054)
Loss on early extinguishment of debt										(1,701)	(39,278)
Equity in earnings									55,096	172,823	144,789
Net (loss) income									(4,086)	124,611	53,605
Preferred stock dividends									(27,245)	(27,245)	(27,245)
Net Income Loss Available To Common Unit holders Basic									(31,331)	97,366	26,360
Subsidiaries [Member] | Subsidiary Guarantors [Member]
Revenues:
Base rent									268,433	267,454	248,719
Recoveries from tenants									127,877	115,185	94,794
Other revenues									1,787	1,657	1,668
Total revenues									398,097	384,296	345,181
Expenses:
Property operating costs									131,644	123,140	108,536
Real estate taxes and insurance									19,942	13,323	13,931
Depreciation and amortization									94,371	90,770	88,556
General and administrative									57	82	97
Impairment of Long-Lived Assets to be Disposed of									119,267
Other expenses									133	1,526	304
Total expenses									365,414	228,841	211,424
Operating income									32,683	155,455	133,757
Interest income									0	0	20
Interest:
Expense incurred									1,327	4,323	351
Amortization of deferred financing costs									107	273	(167)
Loss on early extinguishment of debt										0	(1,700)
Equity in earnings									0	0	0
Net (loss) income									34,117	160,051	132,261
Preferred stock dividends									0	0	0
Net Income Loss Available To Common Unit holders Basic									34,117	160,051	132,261
Subsidiaries [Member] | Subsidiary Non-Guarantors [Member]
Revenues:
Base rent									30,302	18,413	17,126
Recoveries from tenants									11,660	9,668	9,477
Other revenues									12,621	5,489	3,613
Total revenues									54,583	33,570	30,216
Expenses:
Property operating costs									16,598	11,822	10,227
Real estate taxes and insurance									1,393	872	449
Depreciation and amortization									9,630	5,947	4,421
General and administrative									433	940	559
Impairment of Long-Lived Assets to be Disposed of									3,205
Other expenses									10,725	4,338	2,718
Total expenses									41,984	23,919	18,374
Operating income									12,599	9,651	11,842
Interest income									0	1	0
Interest:
Expense incurred									8,184	3,200	814
Amortization of deferred financing costs									196	(80)	(128)
Loss on early extinguishment of debt										0	0
Equity in earnings									0	0	0
Net (loss) income									20,979	12,772	12,528
Preferred stock dividends									0	0	0
Net Income Loss Available To Common Unit holders Basic									20,979	12,772	12,528
Subsidiaries [Member] | Eliminations [Member]
Revenues:
Base rent									(18,211)	(17,650)	(15,451)
Recoveries from tenants									0	0	0
Other revenues									(130)	(123)	(138)
Total revenues									(18,341)	(17,773)	(15,589)
Expenses:
Property operating costs									(18,191)	(17,623)	(15,439)
Real estate taxes and insurance									0	0	0
Depreciation and amortization									0	0	0
General and administrative									0	0	0
Impairment of Long-Lived Assets to be Disposed of									0
Other expenses									(150)	(150)	(150)
Total expenses									(18,341)	(17,773)	(15,589)
Operating income									0	0	0
Interest income									0	0	265
Interest:
Expense incurred									0	0	(265)
Amortization of deferred financing costs									0	0	0
Loss on early extinguishment of debt										0	0
Equity in earnings									(55,096)	(172,823)	(144,789)
Net (loss) income									(55,096)	(172,823)	(144,789)
Preferred stock dividends									0	0	0
Net Income Loss Available To Common Unit holders Basic									$ (55,096)	$ (172,823)	$ (144,789)

18. Supplemental Consolidatin91

18. Supplemental Consolidating Financial Data for Subsidiary Guarantors of the Unsecured Notes Supplemental Consodlidating Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Supplemental Consolidating Statements Of Cash Flows [Line Items]
Net Cash Provided by (Used in) Operating Activities	$ 255,021	$ 244,513	$ 193,761
Investments in real estate – development	(217,339)	(265,374)	(129,332)
Payments to Acquire Land	(8,600)	0	(14,186)
Interest capitalized for real estate under development	(11,564)	(9,644)	(3,774)
Improvements to real estate	(3,459)	(1,916)	(5,757)
Additions to non-real estate property	(753)	(316)	(71)
Net cash used in investing activities	(241,715)	(277,250)	(153,120)
Proceeds from line of credit	120,000	60,000	102,000
Repayments	(180,000)	0	(120,000)
Proceeds	0	0	115,000
Lump sum payoffs	0	0	(138,300)
Repayments of Secured Debt	0	0	(1,300)
Proceeds	0	96,000	154,000
Proceeds	248,012	0	600,000
Repayments	0	0	(550,000)
Payments of financing costs	(4,740)	(3,829)	(18,200)
Payments for early extinguishment of debt	0	0	(32,544)
Equity compensation (payments) proceeds	249	4,363	1,711
Common stock repurchases	(31,912)	0	(37,792)
Net Cash Provided by (Used in) Financing Activities	(11,674)	23,602	(25,486)
Cash and Cash Equivalents, Period Increase (Decrease)	1,632	(9,135)	15,155
Cash and cash equivalents, ending	31,230	29,598	38,733
Subsidiaries [Member]
Supplemental Consolidating Statements Of Cash Flows [Line Items]
Net Cash Provided by (Used in) Operating Activities	255,024	244,514	193,761
Investments in real estate – development	(217,339)	(265,374)	(129,332)
Payments to Acquire Land	(8,600)	0	(14,186)
Investments in affiliates	0	0	0
Interest capitalized for real estate under development	(11,564)	(9,644)	(3,774)
Improvements to real estate	(3,459)	(1,916)	(5,757)
Additions to non-real estate property	(753)	(316)	(71)
Net cash used in investing activities	(241,715)	(277,250)	(153,120)
Proceeds from line of credit	120,000	60,000	102,000
Repayments	(180,000)	0	(120,000)
Proceeds	0	0	115,000
Lump sum payoffs	0	0	(138,300)
Repayments of Secured Debt	0	0	(1,300)
Proceeds	0	96,000	154,000
Proceeds	248,012	0	600,000
Repayments	0	0	(550,000)
Payments of financing costs	(4,740)	(3,829)	(18,123)
Payments for early extinguishment of debt	0	0	(32,544)
Equity compensation (payments) proceeds	249	4,363	1,711
Common stock repurchases	(31,912)	0	(37,792)
Distributions	(163,283)	(132,932)	(100,061)
Net Cash Provided by (Used in) Financing Activities	(11,674)	23,602	(25,409)
Cash and Cash Equivalents, Period Increase (Decrease)	1,635	(9,134)	15,232
Cash and cash equivalents, ending	27,015	25,380	34,514
Subsidiaries [Member] | Operating Partnership [Member]
Supplemental Consolidating Statements Of Cash Flows [Line Items]
Net Cash Provided by (Used in) Operating Activities	(55,999)	(40,234)	(48,725)
Investments in real estate – development	(415)	(404)	(9)
Payments to Acquire Land	0		0
Investments in affiliates	68,074	5,654	62,508
Interest capitalized for real estate under development	(27)	(10)	0
Improvements to real estate	0	0	0
Additions to non-real estate property	(93)	(20)	(6)
Net cash used in investing activities	67,539	5,220	62,493
Proceeds from line of credit	120,000	60,000	102,000
Repayments	(180,000)		(120,000)
Proceeds			0
Lump sum payoffs			0
Repayments of Secured Debt			0
Proceeds		96,000	154,000
Proceeds	248,012		600,000
Repayments			(550,000)
Payments of financing costs	(4,715)	(3,514)	(16,419)
Payments for early extinguishment of debt			(32,544)
Equity compensation (payments) proceeds	249	4,363	1,711
Common stock repurchases	(31,912)		(37,792)
Distributions	(163,283)	(132,932)	(100,061)
Net Cash Provided by (Used in) Financing Activities	(11,649)	23,917	895
Cash and Cash Equivalents, Period Increase (Decrease)	(109)	(11,097)	14,663
Cash and cash equivalents, ending	21,697	21,806	32,903
Subsidiaries [Member] | Subsidiary Guarantors [Member]
Supplemental Consolidating Statements Of Cash Flows [Line Items]
Net Cash Provided by (Used in) Operating Activities	278,557	264,409	225,903
Investments in real estate – development	(8,996)	(111,791)	(50,827)
Payments to Acquire Land	0		0
Investments in affiliates	(264,211)	(146,188)	(28,856)
Interest capitalized for real estate under development	(1,327)	(4,323)	(1,399)
Improvements to real estate	(3,401)	(1,850)	(5,513)
Additions to non-real estate property	(622)	(257)	(65)
Net cash used in investing activities	(278,557)	(264,409)	(86,660)
Proceeds from line of credit	0	0	0
Repayments	0		0
Proceeds			0
Lump sum payoffs			(138,300)
Repayments of Secured Debt			(1,300)
Proceeds		0	0
Proceeds	0		0
Repayments			0
Payments of financing costs	0	0	(4)
Payments for early extinguishment of debt			0
Equity compensation (payments) proceeds	0	0	0
Common stock repurchases	0		0
Distributions	0	0	0
Net Cash Provided by (Used in) Financing Activities	0	0	(139,604)
Cash and Cash Equivalents, Period Increase (Decrease)	0	0	(361)
Cash and cash equivalents, ending	0	0	0
Subsidiaries [Member] | Subsidiary Non-Guarantors [Member]
Supplemental Consolidating Statements Of Cash Flows [Line Items]
Net Cash Provided by (Used in) Operating Activities	32,466	20,339	16,583
Investments in real estate – development	(207,928)	(153,179)	(78,496)
Payments to Acquire Land	(8,600)		(14,186)
Investments in affiliates	196,137	140,534	(33,652)
Interest capitalized for real estate under development	(10,210)	(5,311)	(2,375)
Improvements to real estate	(58)	(66)	(244)
Additions to non-real estate property	(38)	(39)	0
Net cash used in investing activities	(30,697)	(18,061)	(128,953)
Proceeds from line of credit	0	0	0
Repayments	0		0
Proceeds			115,000
Lump sum payoffs			0
Repayments of Secured Debt			0
Proceeds		0	0
Proceeds	0		0
Repayments			0
Payments of financing costs	(25)	(315)	(1,700)
Payments for early extinguishment of debt			0
Equity compensation (payments) proceeds	0	0	0
Common stock repurchases	0		0
Distributions	0	0	0
Net Cash Provided by (Used in) Financing Activities	(25)	(315)	113,300
Cash and Cash Equivalents, Period Increase (Decrease)	1,744	1,963	930
Cash and cash equivalents, ending	5,318	3,574	1,611
Subsidiaries [Member] | Eliminations [Member]
Supplemental Consolidating Statements Of Cash Flows [Line Items]
Net Cash Provided by (Used in) Operating Activities	0	0	0
Investments in real estate – development	0	0	0
Payments to Acquire Land	0		0
Investments in affiliates	0	0	0
Interest capitalized for real estate under development	0	0	0
Improvements to real estate	0	0	0
Additions to non-real estate property	0	0	0
Net cash used in investing activities	0	0	0
Proceeds from line of credit	0	0	0
Repayments	0		0
Proceeds			0
Lump sum payoffs			0
Repayments of Secured Debt			0
Proceeds		0	0
Proceeds	0		0
Repayments			0
Payments of financing costs	0	0	0
Payments for early extinguishment of debt			0
Equity compensation (payments) proceeds	0	0	0
Common stock repurchases	0		0
Distributions	0	0	0
Net Cash Provided by (Used in) Financing Activities	0	0	0
Cash and Cash Equivalents, Period Increase (Decrease)	0	0	0
Cash and cash equivalents, ending	$ 0	$ 0	$ 0

Schedule II - Consolidated Al92

Schedule II - Consolidated Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Valuation and Qualifying Accounts Disclosure [Line Items]
Allowance for doubtful accounts, Balance at Beginning of Period	$ 8,520	$ 3,700	$ 2,961
Charges to operations	372	4,829	739
Net recovery (Deductions)	(3,651)	(9)	0
Allowance for doubtful accounts, Balance at End of Period	$ 5,241	$ 8,520	$ 3,700

Schedule III - Consolidated R93

Schedule III - Consolidated Real Estate and Accumulated Depreciation Real Estate and Accumulated Depreciation (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Amount of Encumbrances		$ 115,000
Real Estate and Accumulated Depreciation, Initial Cost of Land		131,107
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements		3,088,359
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs		(727)
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Improvements		(86,661)
Real Estate and Accumulated Depreciation, Carrying Amount of Land		130,380
Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements		3,001,698
Real Estate and Accumulated Depreciation, Carrying Amount of Land and Buildings and Improvements		3,132,078	$ 3,066,297	$ 2,799,010	$ 2,607,630
Real Estate and Accumulated Depreciation, Accumulated Depreciation		560,837	$ 504,869	$ 413,394	$ 325,740
Real Estate, Federal Income Tax Basis		2,590,000
ACC2 [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Amount of Encumbrances	[1]	0
Real Estate and Accumulated Depreciation, Initial Cost of Land	[1]	2,500
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	[1]	157,100
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	[1]	0
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Improvements	[1]	(2,908)
Real Estate and Accumulated Depreciation, Carrying Amount of Land	[1]	2,500
Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	[1]	154,192
Real Estate and Accumulated Depreciation, Carrying Amount of Land and Buildings and Improvements	[1]	156,692
Real Estate and Accumulated Depreciation, Accumulated Depreciation	[1]	$ 50,969
Real Estate and Accumulated Depreciation, Year of Construction		2,005
Real Estate And Accumulated Depreciation, Year Acquired		2,001
ACC3 [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Amount of Encumbrances	[2]	$ 115,000
Real Estate and Accumulated Depreciation, Initial Cost of Land	[2]	1,071
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	[2]	92,631
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	[2]	0
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Improvements	[2]	3,346
Real Estate and Accumulated Depreciation, Carrying Amount of Land	[2]	1,071
Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	[2]	95,977
Real Estate and Accumulated Depreciation, Carrying Amount of Land and Buildings and Improvements	[2]	97,048
Real Estate and Accumulated Depreciation, Accumulated Depreciation	[2]	$ 32,723
Real Estate and Accumulated Depreciation, Year of Construction		2,006
Real Estate And Accumulated Depreciation, Year Acquired		2,001
ACC4 [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Amount of Encumbrances	[1]	$ 0
Real Estate and Accumulated Depreciation, Initial Cost of Land	[1]	6,600
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	[1]	535,526
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	[1]	0
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Improvements	[1]	3,126
Real Estate and Accumulated Depreciation, Carrying Amount of Land	[1]	6,600
Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	[1]	538,652
Real Estate and Accumulated Depreciation, Carrying Amount of Land and Buildings and Improvements	[1]	545,252
Real Estate and Accumulated Depreciation, Accumulated Depreciation	[1]	$ 157,174
Real Estate and Accumulated Depreciation, Year of Construction		2,007
Real Estate And Accumulated Depreciation, Year Acquired		2,006
ACC5 [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Amount of Encumbrances	[1]	$ 0
Real Estate and Accumulated Depreciation, Initial Cost of Land	[1]	6,443
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	[1]	292,369
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	[1]	0
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Improvements	[1]	6,399
Real Estate and Accumulated Depreciation, Carrying Amount of Land	[1]	6,443
Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	[1]	298,768
Real Estate and Accumulated Depreciation, Carrying Amount of Land and Buildings and Improvements	[1]	305,211
Real Estate and Accumulated Depreciation, Accumulated Depreciation	[1]	$ 60,744
Real Estate And Accumulated Depreciation, Year Acquired		2,007
ACC6 [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Amount of Encumbrances	[1]	$ 0
Real Estate and Accumulated Depreciation, Initial Cost of Land	[1]	5,518
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	[1]	215,235
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	[1]	0
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Improvements	[1]	1,462
Real Estate and Accumulated Depreciation, Carrying Amount of Land	[1]	5,518
Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	[1]	216,697
Real Estate and Accumulated Depreciation, Carrying Amount of Land and Buildings and Improvements	[1]	222,215
Real Estate and Accumulated Depreciation, Accumulated Depreciation	[1]	$ 27,699
Real Estate And Accumulated Depreciation, Year Acquired		2,007
ACC7 Phase I and II [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Amount of Encumbrances	[1]	$ 0
Real Estate and Accumulated Depreciation, Initial Cost of Land	[1]	4,876
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements		167,766
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	[1]	0
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Improvements	[1]	0
Real Estate and Accumulated Depreciation, Carrying Amount of Land	[1]	4,876
Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	[1]	167,766
Real Estate and Accumulated Depreciation, Carrying Amount of Land and Buildings and Improvements	[1]	172,642
Real Estate and Accumulated Depreciation, Accumulated Depreciation	[1]	$ 4,806
Real Estate And Accumulated Depreciation, Year Acquired		2,011
CH1 [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Amount of Encumbrances	[1]	$ 0
Real Estate and Accumulated Depreciation, Initial Cost of Land	[1]	23,611
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	[1]	357,194
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	[1]	0
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Improvements	[1]	1,545
Real Estate and Accumulated Depreciation, Carrying Amount of Land	[1]	23,611
Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	[1]	358,739
Real Estate and Accumulated Depreciation, Carrying Amount of Land and Buildings and Improvements	[1]	382,350
Real Estate and Accumulated Depreciation, Accumulated Depreciation	[1]	$ 70,407
Real Estate And Accumulated Depreciation, Year Acquired		2,007
CH2 Phase I [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Amount of Encumbrances		$ 0
Real Estate and Accumulated Depreciation, Initial Cost of Land	[1]	3,998
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	[1]	71,778
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	[1]	0
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Improvements	[1]	69
Real Estate and Accumulated Depreciation, Carrying Amount of Land	[1]	3,998
Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	[1]	71,847
Real Estate and Accumulated Depreciation, Carrying Amount of Land and Buildings and Improvements	[1]	75,845
Real Estate and Accumulated Depreciation, Accumulated Depreciation	[1]	$ 1,212
Real Estate and Accumulated Depreciation, Year of Construction		2,015
Real Estate And Accumulated Depreciation, Year Acquired		2,013
NJ1 Phase I [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Amount of Encumbrances	[1]	$ 0
Real Estate and Accumulated Depreciation, Initial Cost of Land	[1]	4,311
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	[1]	190,970
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	[1]	(727)
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Improvements	[1]	(117,749)
Real Estate and Accumulated Depreciation, Carrying Amount of Land	[1]	3,584
Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	[1]	73,221
Real Estate and Accumulated Depreciation, Carrying Amount of Land and Buildings and Improvements	[1]	76,805
Real Estate and Accumulated Depreciation, Accumulated Depreciation	[1]	$ 0
Real Estate and Accumulated Depreciation, Year of Construction		2,010
Real Estate And Accumulated Depreciation, Year Acquired		2,007
SC1 [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Amount of Encumbrances	[1]	$ 0
Real Estate and Accumulated Depreciation, Initial Cost of Land	[1]	20,202
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	[1]	429,572
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	[1]	0
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Improvements	[1]	2,985
Real Estate and Accumulated Depreciation, Carrying Amount of Land	[1]	20,202
Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	[1]	432,557
Real Estate and Accumulated Depreciation, Carrying Amount of Land and Buildings and Improvements	[1]	452,759
Real Estate and Accumulated Depreciation, Accumulated Depreciation	[1]	$ 39,013
Real Estate And Accumulated Depreciation, Year Acquired		2,007
VA3 [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Amount of Encumbrances	[1]	$ 0
Real Estate and Accumulated Depreciation, Initial Cost of Land	[1]	9,000
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	[1]	172,881
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	[1]	0
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Improvements	[1]	6,140
Real Estate and Accumulated Depreciation, Carrying Amount of Land	[1]	9,000
Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	[1]	179,021
Real Estate and Accumulated Depreciation, Carrying Amount of Land and Buildings and Improvements	[1]	188,021
Real Estate and Accumulated Depreciation, Accumulated Depreciation	[1]	$ 65,458
Real Estate and Accumulated Depreciation, Year of Construction		2,003
Real Estate And Accumulated Depreciation, Year Acquired		2,003
VA4 [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Amount of Encumbrances	[1]	$ 0
Real Estate and Accumulated Depreciation, Initial Cost of Land	[1]	6,800
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	[1]	140,575
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	[1]	0
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Improvements	[1]	8,924
Real Estate and Accumulated Depreciation, Carrying Amount of Land	[1]	6,800
Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	[1]	149,499
Real Estate and Accumulated Depreciation, Carrying Amount of Land and Buildings and Improvements	[1]	156,299
Real Estate and Accumulated Depreciation, Accumulated Depreciation	[1]	$ 50,632
Real Estate and Accumulated Depreciation, Year of Construction		2,005
Real Estate And Accumulated Depreciation, Year Acquired		2,005
Operating Properties [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Amount of Encumbrances		$ 115,000
Real Estate and Accumulated Depreciation, Initial Cost of Land		94,930
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements		2,823,597
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs		(727)
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Improvements		(86,661)
Real Estate and Accumulated Depreciation, Carrying Amount of Land		94,203
Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements		2,736,936
Real Estate and Accumulated Depreciation, Carrying Amount of Land and Buildings and Improvements		2,831,139
Real Estate and Accumulated Depreciation, Accumulated Depreciation		560,837
ACC7 Phase III and IV [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Amount of Encumbrances		0
Real Estate and Accumulated Depreciation, Initial Cost of Land		4,876
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements		115,739
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs		0
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Improvements		0
Real Estate and Accumulated Depreciation, Carrying Amount of Land		4,876
Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements		115,739
Real Estate and Accumulated Depreciation, Carrying Amount of Land and Buildings and Improvements		120,615
Real Estate and Accumulated Depreciation, Accumulated Depreciation		$ 0
Real Estate And Accumulated Depreciation, Year Acquired		2,011
CH2 Phase II and III [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Amount of Encumbrances		$ 0
Real Estate and Accumulated Depreciation, Initial Cost of Land		10,395
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements		131,821
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs		0
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Improvements		0
Real Estate and Accumulated Depreciation, Carrying Amount of Land		10,395
Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements		131,821
Real Estate and Accumulated Depreciation, Carrying Amount of Land and Buildings and Improvements		142,216
Real Estate and Accumulated Depreciation, Accumulated Depreciation		$ 0
Real Estate And Accumulated Depreciation, Year Acquired		2,013
NJ1 Phase II [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Amount of Encumbrances	[1]	$ 0
Real Estate and Accumulated Depreciation, Initial Cost of Land		3,584
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	[1]	14,689
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	[1]	0
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Improvements	[1]	0
Real Estate and Accumulated Depreciation, Carrying Amount of Land	[1]	3,584
Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	[1]	14,689
Real Estate and Accumulated Depreciation, Carrying Amount of Land and Buildings and Improvements	[1]	18,273
Real Estate and Accumulated Depreciation, Accumulated Depreciation		$ 0
Real Estate And Accumulated Depreciation, Year Acquired		2,007
ACC8 [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Amount of Encumbrances		$ 0
Real Estate and Accumulated Depreciation, Initial Cost of Land		3,785
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements		458
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs		0
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Improvements		0
Real Estate and Accumulated Depreciation, Carrying Amount of Land		3,785
Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements		458
Real Estate and Accumulated Depreciation, Carrying Amount of Land and Buildings and Improvements		4,243
Real Estate and Accumulated Depreciation, Accumulated Depreciation		$ 0
Real Estate And Accumulated Depreciation, Year Acquired		2,007
CH3 [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Amount of Encumbrances		$ 0
Real Estate and Accumulated Depreciation, Initial Cost of Land		8,305
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements		15
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs		0
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Improvements		0
Real Estate and Accumulated Depreciation, Carrying Amount of Land		8,305
Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements		15
Real Estate and Accumulated Depreciation, Carrying Amount of Land and Buildings and Improvements		8,320
Real Estate and Accumulated Depreciation, Accumulated Depreciation		$ 0
Real Estate And Accumulated Depreciation, Year Acquired		2,015
SC2 [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Amount of Encumbrances	[1]	$ 0
Real Estate and Accumulated Depreciation, Initial Cost of Land		5,232
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements	[1]	2,040
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs	[1]	0
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Improvements	[1]	0
Real Estate and Accumulated Depreciation, Carrying Amount of Land	[1]	5,232
Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements	[1]	2,040
Real Estate and Accumulated Depreciation, Carrying Amount of Land and Buildings and Improvements	[1]	7,272
Real Estate and Accumulated Depreciation, Accumulated Depreciation		$ 0
Real Estate And Accumulated Depreciation, Year Acquired		2,007
Development Properties [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Amount of Encumbrances		$ 0
Real Estate and Accumulated Depreciation, Initial Cost of Land		36,177
Real Estate and Accumulated Depreciation, Initial Cost of Buildings and Improvements		264,762
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Carrying Costs		0
Real Estate and Accumulated Depreciation, Costs Capitalized Subsequent to Acquisition, Improvements		0
Real Estate and Accumulated Depreciation, Carrying Amount of Land		36,177
Real Estate and Accumulated Depreciation, Carrying Amount of Buildings and Improvements		264,762
Real Estate and Accumulated Depreciation, Carrying Amount of Land and Buildings and Improvements		300,939
Real Estate and Accumulated Depreciation, Accumulated Depreciation		$ 0
Minimum [Member] | ACC5 [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Year of Construction	[1]	2,009
Minimum [Member] | ACC6 [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Year of Construction	[1]	2,011
Minimum [Member] | ACC7 Phase I and II [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Year of Construction	[1]	2,014
Minimum [Member] | CH1 [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Year of Construction	[1]	2,008
Minimum [Member] | SC1 [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Year of Construction	[1]	2,011
Maximum [Member] | ACC5 [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Year of Construction	[1]	2,010
Maximum [Member] | ACC6 [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Year of Construction	[1]	2,013
Maximum [Member] | ACC7 Phase I and II [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Year of Construction	[1]	2,015
Maximum [Member] | CH1 [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Year of Construction	[1]	2,012
Maximum [Member] | SC1 [Member]
Real Estate and Accumulated Depreciation [Line Items]
Real Estate and Accumulated Depreciation, Year of Construction	[1]	2,015
[1]	(1) The subsidiaries that own these data centers and development properties are guarantors of our Unsecured Notes due 2021 and 2023, our Unsecured Credit Facility and our Unsecured Term Loan.
[2]	(2) The subsidiary that owns this data center is encumbered by our ACC3 Term Loan.

Schedule III - Consolidated R94

Schedule III - Consolidated Real Estate and Accumulated Depreciation Reconciliation of Real Estate Assets and Accumulated Depreciation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
SEC Schedule III, Real Estate and Accumulated Depreciation Disclosure [Abstract]
Real estate assets Balance, beginning of period	$ 3,066,297	$ 2,799,010	$ 2,607,630
Additions - property acquisitions	8,600	0	14,186
Additions - improvements	221,588	267,357	177,194
Deductions - write offs	(164,407)	(70)	0
Real estate assets Balance, end of period	3,132,078	3,066,297	2,799,010
Accumulated depreciation Balance, beginning of period	504,869	413,394	325,740
Additions - depreciation	97,988	91,545	87,654
Deductions - write offs	(42,020)	(70)	0
Accumulated depreciation Balance, end of period	$ 560,837	$ 504,869	$ 413,394