Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock	Redeemable Limited Partner Common Units	Additional Paid-in Capital	Accumulated Dividends in Excess of Earnings	Accumulated Other Comprehensive Income (Loss), net	Total Stockholders’ Equity	Noncontrolling Interests in Operating Partnership	Noncontrolling Interests in Consolidated Joint Ventures	Total Noncontrolling Interests	DFT Company	DFT Company Total Stockholders’ Equity	DFT Company Potentially dilutive Series C Cumulative Redeemable Perpetual Preferred Units Preferred Stock
Balance at Beginning of Period at Dec. 31, 2014	$ 3,914,238	$ 1,048,121	$ 1,349		$ 3,970,439	$ (1,096,607)	$ (45,046)	$ 3,878,256	$ 29,191	$ 6,791	$ 35,982
Balance (shares) at Dec. 31, 2014			135,626,255
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of common units to common stock			$ 2		1,841			1,843	(1,843)		(1,843)
Conversion of common units to common stock (shares)			156,008
Issuance of unvested restricted stock, net of forfeitures (in shares)			72,673
Common stock offering costs	799				799			799
Issuance of series J preferred stock, net of offering costs	896				896			896
Exercise of stock options (shares)			29,311
Issuance of common stock in exchange for cash and debentures (in shares)			10,500,000
Issuance of preferred stock in connection with merger	675,577		$ 105		675,472			675,577
Issuance of preferred stock, net of offering costs	242,014	242,014						242,014
Reclassification of vested share-based awards	14,375				14,375			14,375
Adjustment to redeemable noncontrolling interests—operating partnership					(8,602)			(8,602)	8,602		8,602
Dividends declared on preferred stock	(79,423)					(79,423)		(79,423)
Dividends and distributions on common stock and common and incentive units	(480,541)					(470,748)		(470,748)	(9,793)		(9,793)
Distributions to noncontrolling interests in consolidated joint ventures, net of contributions	(493)									(493)	(493)
Net income	301,591					296,689		296,689	4,442	460	4,902
Other comprehensive income— foreign currency translation adjustments	(51,745)						(50,775)	(50,775)	(970)		(970)
Other comprehensive income— fair value of interest rate swaps and foreign currency hedges	(3,407)						(3,338)	(3,338)	(69)		(69)
Other comprehensive income— reclassification of accumulated other comprehensive loss to interest expense	2,621						2,569	2,569	52		52
Balance at End of Period at Dec. 31, 2015	4,536,502	1,290,135	$ 1,456		4,655,220	(1,350,089)	(96,590)	4,500,132	29,612	6,758	36,370
Balance (shares) at Dec. 31, 2015			146,384,247
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of common units to common stock			$ 5		5,237			5,242	(5,242)		(5,242)
Conversion of common units to common stock (shares)			430,493
Issuance of unvested restricted stock, net of forfeitures (in shares)			120,082
Issuance of series J preferred stock, net of offering costs	1,380				1,380			1,380
Redemption of series F preferred units	(287,500)	(277,172)				(10,328)		(287,500)
Exercise of stock options (shares)			33,948
Issuance of common stock in exchange for cash and debentures (in shares)			12,000,000
Issuance of preferred stock in connection with merger	1,085,444		$ 120		1,085,324			1,085,444
Issuance of preferred stock, net of offering costs	(2)	(2)						(2)
Reclassification of vested share-based awards	24,113				24,113			24,113
Adjustment to redeemable noncontrolling interests—operating partnership					(10,125)			(10,125)	10,125		10,125
Dividends declared on preferred stock	(83,771)					(83,771)		(83,771)
Dividends and distributions on common stock and common and incentive units	(538,888)					(529,419)		(529,419)	(9,469)		(9,469)
Distributions to noncontrolling interests in consolidated joint ventures, net of contributions	(527)									(527)	(527)
Net income	431,852					426,187		426,187	5,298	367	5,665
Other comprehensive income— foreign currency translation adjustments	(86,621)						(85,300)	(85,300)	(1,321)		(1,321)
Other comprehensive income— fair value of interest rate swaps and foreign currency hedges	41,998						41,395	41,395	603		603
Other comprehensive income— reclassification of accumulated other comprehensive loss to interest expense	4,968						4,890	4,890	78		78
Balance at End of Period at Dec. 31, 2016	5,132,297	1,012,961	$ 1,582		5,764,497	(1,547,420)	(135,605)	5,096,015	29,684	6,598	36,282
Balance (shares) at Dec. 31, 2016			159,019,118.000
Units issued in connection with employee stock purchase plan	5,143				5,143			5,143
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of common units to common stock			$ 6		10,003			10,009	(10,009)		(10,009)
Conversion of common units to common stock (shares)			562,582
Issuance of unvested restricted stock, net of forfeitures (in shares)			249,050
Issuance of common units in connection with DFT merger	5,924,124		$ 432	$ 66,259	5,247,126			5,247,558	676,566		676,566
Issuance of common units in connection with DFT merger (in shares)			43,175,629
Issuance of series J preferred stock, net of offering costs	729				729			729
Redemption of series F preferred units	$ (182,500)	(176,191)				(6,309)		(182,500)
Exercise of stock options (shares)			17,668
Shares issued under employee stock purchase plan			71,253
Issuance of common stock in exchange for cash and debentures (in shares)	6,111,770		2,375,000
Issuance of preferred stock in connection with merger	$ 211,897		$ 24		211,873			211,897				$ 219,250	$ 219,250	$ 219,250
Issuance of series J preferred units, net of offering costs	193,540	193,540						193,540
Reclassification of vested share-based awards	27,981				27,981			27,981
Noncontrolling Interest in Net Income (Loss) Operating Partnerships, Redeemable	12,357			(12,357)	4,166			4,166	8,191		8,191
Adjustment to redeemable noncontrolling interests—operating partnership	0				(10,057)			(10,057)	10,057		10,057
Dividends declared on preferred stock	(68,802)					(68,802)		(68,802)
Dividends and distributions on common stock and common and incentive units	(701,974)					(681,280)		(681,280)	(20,694)		(20,694)
Distributions to noncontrolling interests in consolidated joint ventures, net of contributions	(8,593)									(8,593)	(8,593)
Net income	256,267					248,259		248,259	3,770	4,238	8,008
Other comprehensive income— foreign currency translation adjustments	28,709						28,272	28,272	437		437
Other comprehensive income— fair value of interest rate swaps and foreign currency hedges	(3,434)						(3,513)	(3,513)	79		79
Other comprehensive income— reclassification of accumulated other comprehensive loss to interest expense	2,459						2,414	2,414	45		45
Balance at End of Period at Dec. 31, 2017	$ 11,049,450	$ 1,249,560	$ 2,044	$ 53,902	$ 11,261,461	$ (2,055,552)	$ (108,432)	$ 10,349,081	$ 698,126	$ 2,243	$ 700,369
Balance (shares) at Dec. 31, 2017			205,470,300