Condensed Consolidated Statement of Noncontrolling Interests and Equity - USD ($) $ in Thousands	Total	Redemption of Operating Partnership units for cash	Series A Preferred Operating Partnership	Series B Preferred Operating Partnership	Series C Preferred Operating Partnership	Series D Preferred Operating Partnership	Operating Partnership	Operating Partnership Redemption of Operating Partnership units for stock	Operating Partnership Redemption of Operating Partnership units for cash	Other	Common Stock	Common Stock Redemption of Operating Partnership units for stock	Additional Paid-in Capital	Additional Paid-in Capital Redemption of Operating Partnership units for stock	Additional Paid-in Capital Redemption of Operating Partnership units for cash	Accumulated Other Comprehensive Income	Accumulated Deficit
Balance, beginning of period (in shares) at Dec. 31, 2017											126,007,091
Balance, beginning of period at Dec. 31, 2017	$ 2,723,807		$ 14,940	$ 41,902	$ 10,730	$ 92,064	$ 213,301			$ 119	$ 1,260		$ 2,569,485			$ 33,290	$ (253,284)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of options (in shares)											31,525
Issuance of common stock upon the exercise of options	799												799
Restricted stock grants issued (in shares)											31,136
Restricted stock grants issued	0										$ 0		0
Restricted stock grants canceled (in shares)											(770)
Compensation expense related to stock-based awards	2,726												2,726
Repayment of receivable for preferred operating units pledged as collateral on loan	495				495
Redemption of Operating Partnership units		$ (2,558)							$ (1,126)						$ (1,432)
Noncontrolling interest in consolidated joint venture	120									120
Repurchase of equity portion of 2013 exchangeable senior notes	(21,000)												(21,000)
Net income	95,430		1,156	629	676	929	3,784										88,256
Other comprehensive income (loss)	23,063		144				938									21,981
Distributions to Operating Partnership units held by noncontrolling interests	(7,909)		(1,254)	(629)	(676)	(929)	(4,421)
Dividends paid on common stock	(98,327)																(98,327)
Balance, end of period (in shares) at Mar. 31, 2018											126,068,982
Balance, end of period at Mar. 31, 2018	$ 2,716,646		14,986	41,902	11,225	92,064	212,476			239	$ 1,260		2,550,578			55,271	(263,355)
Balance, beginning of period (in shares) at Dec. 31, 2018	127,103,750										127,103,750
Balance, beginning of period at Dec. 31, 2018	$ 2,785,422		14,756	41,902	4,374	92,064	218,362			240	$ 1,271		2,640,705			34,650	(262,902)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of options (in shares)											169,021
Issuance of common stock upon the exercise of options	1,757												1,754
Restricted stock grants issued (in shares)											35,022
Restricted stock grants issued	0		0								$ 0
Restricted stock grants canceled (in shares)											(1,244)
Compensation expense related to stock-based awards	2,954												2,954
Redemption of Operating Partnership units (in shares)												85,501
Redemption of Operating Partnership units								$ (3,310)						$ 3,310
Issuance of Preferred D Units in the Operating Partnership in conjunction with acquisitions	23,447					23,447
Net income	102,160		1,194	629	308	1,033	4,235			(9)							94,770
Other comprehensive income (loss)	(23,993)		(147)				(1,003)									(22,843)
Distributions to Operating Partnership units held by noncontrolling interests	(8,412)		(1,326)	(629)	(308)	(1,033)	(5,116)
Dividends paid on common stock	$ (109,523)																(109,523)
Balance, end of period (in shares) at Mar. 31, 2019	127,392,050										127,392,050
Balance, end of period at Mar. 31, 2019	$ 2,773,812		$ 14,477	$ 41,902	$ 4,374	$ 115,511	$ 213,168			$ 231	$ 1,274		$ 2,648,723			$ 11,807	$ (277,655)