CONSOLIDATED STATEMENTS OF CASH FLOW $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Cash flow from operating activities:
Net income (loss)	$ (7,175)	$ 1,457	$ 24,685
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	143,354	136,585	120,805
Above/Below Market Lease Amortization	465	865	659
Amortization of deferred loan costs	3,856	3,640	3,285
Amortization of senior notes discount		229	261
Loss on extinguishment of debt		19,912
Equity-based compensation expense	14,972	13,863	10,584
Bad debt expense (recoveries)	(2,275)	3,519	1,752
Write off of deferred loan costs	605	80	224
Deferred tax benefit	(2,970)	(10,742)	(10,171)
Loss on sale of property	6,994
Integration, impairment & restructuring costs	19,575	9,027	1,927
Changes in operating assets and liabilities
Rents and other receivables, net	(6,495)	(12,881)	(17,101)
Prepaid expenses	(3,063)	755	158
Other assets	4,518	282	(561)
Accounts payable and accrued liabilities	8,573	(5,071)	6,290
Advance rents, security deposits and other liabilities	2,069	5,491	5,959
Deferred income	8,270	3,312	5,038
Net cash provided by operating activities	191,273	170,323	153,794
Cash flow from investing activities:
Proceeds from sale of property	2,779
Acquisitions, net of cash acquired	(117,029)	(127,038)	(173,067)
Additions to property and equipment	(484,303)	(307,314)	(279,905)
Net cash used in investing activities	(598,553)	(434,352)	(452,972)
Cash flow from financing activities:
Credit facility proceeds	483,000	888,000	574,000
Credit facility repayments	(362,000)	(696,000)	(459,002)
Debt Proceeds		1,920
5.75% Senior Notes Repayment		(300,000)
4.75% Notes Issuance		400,000
Payment of debt extinguishment costs		(13,218)
Payment of deferred financing costs	(3,964)	(10,862)	(4,177)
Payment of Preferred Stock dividend	(10,728)
Payment of common stock dividends	(82,579)	(74,592)	(62,585)
Distribution to noncontrolling interests	(10,759)	(10,289)	(9,619)
Proceeds from exercise of stock options	246	4,972	858
Payment of tax withholdings related to equity based awards	(2,205)	(4,725)	(2,584)
Principal payments on capital lease obligations	(7,626)	(12,224)	(12,600)
Dulles, VA Vault Capital Lease Repayment		(17,785)
Mortgage principal debt repayments	(66)	(54)
Preferred stock issuance proceeds, net of costs	407,477
Common stock issuance proceeds, net of costs		107,549	275,663
Net cash provided by financing activities	410,796	262,692	299,954
Net increase (decrease) in cash and cash equivalents	3,516	(1,337)	776
Cash and cash equivalents, beginning of period	8,243	9,580	8,804
Cash and cash equivalents, end of period	11,759	8,243	9,580
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Cash paid for interest (excluding deferred financing costs and amounts capitalized)	24,532	29,934	19,897
Noncash investing and financing activities:
Accrued capital additions	76,890	75,965	40,431
Accrued preferred stock dividends	5,939
Accrued deferred financing costs	76	458	39
Accrued equity issuance costs	115	25
Acquisitions, net of cash acquired:
Land		9,363	7,602
Buildings, improvements and equipment	445	14,341	80,975
Construction in Progress	114,283	103,334	62,884
Rents and other receivables, net			(2,042)
Acquired intangibles	2,301		34,521
Deferred costs			4,414
Prepaid expenses			574
Goodwill			(7,895)
Other assets			309
Accounts payable and accrued liabilities			(922)
Advance rents, security deposits and other liabilities			(1,343)
Deferred income			35
Deferred income taxes			6,045
Total acquisitions, net of cash acquired	117,029	127,038	173,067
Qualitytech, LP
Cash flow from operating activities:
Net income (loss)	(7,175)	1,457	24,685
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	143,354	136,585	120,805
Above/Below Market Lease Amortization	465	865	659
Amortization of deferred loan costs	3,856	3,640	3,285
Amortization of senior notes discount		229	261
Loss on extinguishment of debt		19,912
Equity-based compensation expense	14,972	13,863	10,584
Bad debt expense (recoveries)	(2,275)	3,519	1,752
Write off of deferred loan costs	605	80	224
Deferred tax benefit	(2,970)	(10,742)	(10,171)
Loss on sale of property	6,994
Integration, impairment & restructuring costs	19,575	9,027	1,927
Changes in operating assets and liabilities
Rents and other receivables, net	(6,495)	(12,881)	(17,101)
Prepaid expenses	(3,063)	755	158
Other assets	4,518	282	(561)
Accounts payable and accrued liabilities	8,573	(5,071)	6,290
Advance rents, security deposits and other liabilities	2,069	5,491	5,959
Deferred income	8,270	3,312	5,038
Net cash provided by operating activities	191,273	170,323	153,794
Cash flow from investing activities:
Proceeds from sale of property	2,779
Acquisitions, net of cash acquired	(117,029)	(127,038)	(173,067)
Additions to property and equipment	(484,303)	(307,314)	(279,905)
Net cash used in investing activities	(598,553)	(434,352)	(452,972)
Cash flow from financing activities:
Credit facility proceeds	483,000	888,000	574,000
Credit facility repayments	(362,000)	(696,000)	(459,002)
Debt Proceeds		1,920
5.75% Senior Notes Repayment		(300,000)
4.75% Notes Issuance		400,000
Payment of debt extinguishment costs		(13,218)
Payment of deferred financing costs	(3,964)	(10,862)	(4,177)
Payment of Preferred Stock dividend	(10,728)
Payment of cash dividends	(82,579)	(74,592)	(62,585)
Proceeds from exercise of stock options	246	4,972	858
Payment of tax withholdings related to equity based awards	(2,205)	(4,725)	(2,584)
Principal payments on capital lease obligations	(7,626)	(12,224)	(12,600)
Dulles, VA Vault Capital Lease Repayment		(17,785)
Mortgage principal debt repayments	(66)	(54)
Preferred stock issuance proceeds, net of costs	407,477
Common stock issuance proceeds, net of costs		107,549	275,663
Partnership distributions	(10,759)	(10,289)	(9,619)
Net cash provided by financing activities	410,796	262,692	299,954
Net increase (decrease) in cash and cash equivalents	3,516	(1,337)	776
Cash and cash equivalents, beginning of period	8,243	9,580	8,804
Cash and cash equivalents, end of period	11,759	8,243	9,580
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Cash paid for interest (excluding deferred financing costs and amounts capitalized)	24,532	29,934	19,897
Noncash investing and financing activities:
Accrued capital additions	76,890	75,965	40,431
Accrued preferred stock dividends	5,939
Accrued deferred financing costs	76	458	39
Accrued equity issuance costs	115	25
Acquisitions, net of cash acquired:
Land		9,363	7,602
Buildings, improvements and equipment	445	14,341	80,975
Construction in Progress	114,283	103,334	62,884
Rents and other receivables, net			(2,042)
Acquired intangibles	2,301		34,521
Deferred costs			4,414
Prepaid expenses			574
Goodwill			(7,895)
Other assets			309
Accounts payable and accrued liabilities			(922)
Advance rents, security deposits and other liabilities			(1,343)
Deferred income			35
Deferred income taxes			6,045
Total acquisitions, net of cash acquired	$ 117,029	$ 127,038	$ 173,067