Condensed Consolidated Statement of Noncontrolling Interests and Equity - 9 months ended Sep. 30, 2018 - USD ($) $ in Thousands	Total	Series A Preferred Operating Partnership	Series B Preferred Operating Partnership	Series C Preferred Operating Partnership	Series D Preferred Operating Partnership	Operating Partnership	Other	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income	Accumulated Deficit
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)
Balance, beginning of period (in shares) at Dec. 31, 2017	126,007,091							126,007,091
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of options (in shares)								54,575
Issuance of common stock upon the exercise of options	$ 1,169							$ 0	1,169
Restricted stock grants issued (in shares)								84,264
Restricted stock grants issued	1							$ 1
Restricted stock grants canceled (in shares)								(9,379)
Issuance of common stock, net of offering costs (in shares)								343,251
Issuance of common stock, net of offering costs	33,780							$ 3	33,777
Compensation expense related to stock-based awards	8,455								8,455
Repayment of receivable for preferred operating units pledged as collateral on loan	495			495
Issuance of Operating Partnership units in conjunction with acquisitions	1,877					1,877
Redemption of Operating Partnership units for stock						(955)			955
Redemption of Operating Partnership units for stock (in shares)								25,000
Redemption of Operating Partnership units for cash	(2,558)					(1,126)			(1,432)
Noncontrolling interest in consolidated joint venture	122						122
Repurchase of equity portion of 2013 exchangeable senior notes	(31,251)								(31,251)
Net income	337,830	3,793	1,886	2,140	2,786	13,399	(1)				313,827
Other comprehensive income	36,812	233				1,507				35,072
Distributions to Operating Partnership units held by noncontrolling interests	(24,837)	(3,906)	(1,886)	(2,140)	(2,787)	(14,118)
Dividends paid on common stock at $2.50 per share	(315,608)										(315,608)
Balance, end of period at Sep. 30, 2018	$ 2,770,094	$ 15,060	$ 41,902	$ 11,225	$ 92,063	$ 213,885	$ 240	$ 1,264	$ 2,581,158	$ 68,362	$ (255,065)
Balance, end of period (in shares) at Sep. 30, 2018	126,504,802							126,504,802