Condensed Consolidated Statement of Noncontrolling Interests and Equity - USD ($) $ in Thousands	Total	Redemption of Operating Partnership units for cash	Preferred Operating Partnership	Operating Partnership	Operating Partnership Redemption of Operating Partnership units for cash	Operating Partnership Redemption of Operating Partnership units for stock	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 cash	Additional Paid-in Capital Redemption of Operating Partnership units for stock	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		$ 159,636	$ 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 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)
Repurchase of equity portion of exchangeable senior notes	(21,000)									(21,000)
Noncontrolling interest in consolidated joint venture	122						122
Net income	95,430		3,390	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)		(3,488)	(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	2,716,648		160,177	212,476			241	$ 1,260		2,550,578			55,271	(263,355)
Balance, beginning of period (in shares) at Dec. 31, 2017								126,007,091
Balance, beginning of period at Dec. 31, 2017	2,723,807		159,636	213,301			119	$ 1,260		2,569,485			33,290	(253,284)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	337,830
Balance, end of period (in shares) at Sep. 30, 2018								126,504,802
Balance, end of period at Sep. 30, 2018	2,770,094		160,250	213,885			240	$ 1,264		2,581,158			68,362	(255,065)
Balance, beginning of period (in shares) at Mar. 31, 2018								126,068,982
Balance, beginning of period at Mar. 31, 2018	2,716,648		160,177	212,476			241	$ 1,260		2,550,578			55,271	(263,355)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of options (in shares)								23,050
Issuance of common stock upon the exercise of options	371							$ 1		370
Restricted stock grants issued (in shares)								50,334
Restricted stock grants canceled (in shares)								(6,311)
Compensation expense related to stock-based awards	3,116									3,116
Redemption of Operating Partnership units (in shares)									10,000
Redemption of Operating Partnership units						$ (383)						$ 383
Issuance of Operating Partnership units in conjunction with acquisitions	1,877			1,877
Net income	102,713		3,492	4,068										95,153
Other comprehensive income (loss)	8,033		50	324									7,659
Distributions to Operating Partnership units held by noncontrolling interests	(8,468)		(3,615)	(4,853)
Dividends paid on common stock	(108,486)													(108,486)
Balance, end of period (in shares) at Jun. 30, 2018								126,146,055
Balance, end of period at Jun. 30, 2018	2,715,804		160,104	213,509			241	$ 1,261		2,554,447			62,930	(276,688)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock grants issued (in shares)								2,794
Restricted stock grants canceled (in shares)								(2,298)
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	2,613									2,613
Redemption of Operating Partnership units (in shares)									15,000
Redemption of Operating Partnership units						(572)						572
Repurchase of equity portion of exchangeable senior notes	10,251									10,251
Net income	139,687		3,723	5,547			(1)							130,418
Other comprehensive income (loss)	5,716		39	245									5,432
Distributions to Operating Partnership units held by noncontrolling interests	(8,460)		(3,616)	(4,844)
Dividends paid on common stock	(108,795)													(108,795)
Balance, end of period (in shares) at Sep. 30, 2018								126,504,802
Balance, end of period at Sep. 30, 2018	$ 2,770,094		160,250	213,885			240	$ 1,264		2,581,158			68,362	(255,065)
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		153,096	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							$ 3		1,754
Restricted stock grants issued (in shares)								35,022
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 Operating Partnership units in conjunction with acquisitions	23,447		23,447
Net income	102,160		3,164	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)		(3,296)	(5,116)
Dividends paid on common stock	(109,523)													(109,523)
Balance, end of period (in shares) at Mar. 31, 2019								127,392,050
Balance, end of period at Mar. 31, 2019	$ 2,773,812		176,264	213,168			231	$ 1,274		2,648,723			11,807	(277,655)
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		153,096	218,362			240	$ 1,271		2,640,705			34,650	(262,902)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 330,844
Balance, end of period (in shares) at Sep. 30, 2019	129,410,093							129,410,093
Balance, end of period at Sep. 30, 2019	$ 2,907,989		175,918	209,011			346	$ 1,294		2,861,611			(43,439)	(296,752)
Balance, beginning of period (in shares) at Mar. 31, 2019								127,392,050
Balance, beginning of period at Mar. 31, 2019	2,773,812		176,264	213,168			231	$ 1,274		2,648,723			11,807	(277,655)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of options (in shares)								17,042
Issuance of common stock upon the exercise of options	468									468
Restricted stock grants issued (in shares)								53,789
Restricted stock grants issued	2							$ 2
Restricted stock grants canceled (in shares)								(4,786)
Issuance of common stock, net of offering costs (in shares)								930,000
Issuance of common stock, net of offering costs	98,796							$ 9		98,787
Compensation expense related to stock-based awards	3,998									3,998
Redemption of Operating Partnership units (in shares)									125,000
Redemption of Operating Partnership units						(4,823)						4,823
Issuance of Operating Partnership units in conjunction with acquisitions	4,575		4,575
Noncontrolling interest in consolidated joint venture	50						50
Conversion of Preferred C Units in the Operating Partnership for Common Operating Partnership Units			(4,374)	4,374
Net income	112,689		3,129	4,754			(22)							104,828
Other comprehensive income (loss)	(41,302)		(254)	(1,765)									(39,283)
Distributions to Operating Partnership units held by noncontrolling interests	(8,705)		(3,232)	(5,473)
Dividends paid on common stock	(115,572)													(115,572)
Balance, end of period (in shares) at Jun. 30, 2019								128,513,095
Balance, end of period at Jun. 30, 2019	2,828,811		176,108	210,235			259	$ 1,285		2,756,799			(27,476)	(288,399)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon the exercise of options (in shares)								14,850
Issuance of common stock upon the exercise of options	605									605
Restricted stock grants issued (in shares)								5,099
Restricted stock grants issued	0							$ 0
Restricted stock grants canceled (in shares)								(1,269)
Issuance of common stock, net of offering costs (in shares)								849,200
Issuance of common stock, net of offering costs	100,056							$ 9		100,047
Compensation expense related to stock-based awards	3,035									3,035
Repayment of receivable for preferred operating units pledged as collateral on loan	1,211			1,211
Redemption of Operating Partnership units (in shares)									29,118
Redemption of Operating Partnership units						$ (1,125)						$ 1,125
Noncontrolling interest in consolidated joint venture	96						96
Net income	115,995		3,089	4,828			(9)							108,087
Other comprehensive income (loss)	(16,762)		(101)	(698)									(15,963)
Distributions to Operating Partnership units held by noncontrolling interests	(8,618)		(3,178)	(5,440)
Dividends paid on common stock	$ (116,440)													(116,440)
Balance, end of period (in shares) at Sep. 30, 2019	129,410,093							129,410,093
Balance, end of period at Sep. 30, 2019	$ 2,907,989		$ 175,918	$ 209,011			$ 346	$ 1,294		$ 2,861,611			$ (43,439)	$ (296,752)