Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Series A Preferred Operating Partnership [Member]	Series B Preferred Operating Partnership [Member]	Series C Preferred Operating Partnership [Member]	Series D Preferred Operating Partnership [Member]	Common Operating Partnership [Member]	Other [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]	General And Limited Partner, Operating Partnership [Member]	General And Limited Partner, Operating Partnership [Member] Common Operating Partnership [Member]	Series D Preferred Stock [Member] Preferred Partner [Member] Series D Preferred Operating Partnership [Member]
Balance, beginning of period at Dec. 31, 2013	$ 1,931,895	$ 30,202	$ 33,568	$ 17,177	$ 0	$ 91,453	$ 1,025	$ 1,157	$ 1,973,159	$ 10,156	$ (226,002)
Balance, beginning of period (in shares) at Dec. 31, 2013								115,755,527
Issuance of common stock upon the exercise of options	$ 3,095							$ 2	3,093
Issuance of common stock upon the exercise of options (in shares)	211,747							211,747
Restricted stock grants issued	$ 1							$ 1
Restricted stock grants issued (in shares)								117,370
Restricted stock grants cancelled (in shares)								(23,595)
Compensation expense related to stock-based awards	4,984								4,984
Issuance of Operating Partnership units in conjunction with acquisitions	38,809		8,334	13,783	13,710	2,982			0
Issuance of Preferred D Units in the Operating Partnership in conjunction with acquisitions												$ (4,794)	$ 0
Redemption of Operating Partnership units for common stock	0	(10,240)				(398)	0	$ 3	10,635
Redemption of Operating Partnership units for common stock (in shares)								299,190
Issuance of common stock, net of offering costs								$ 0
Issuance of common stock, net of offering costs (in shares)								0
Redemption of Operating Partnership units for cash		(4,794)
Issuance of note receivable to Series C unit holders	(20,230)			(20,230)
Net income	195,896	7,036	2,387	1,551	17	6,538	12				178,355
Other comprehensive income (loss)	(12,061)	(74)				(347)				(11,640)
Tax effect from vesting of restricted stock grants and stock option exercises	3,613								3,613
Distributions to Operating Partnership units held by noncontrolling interests	(19,081)	(7,321)	(2,386)	(1,551)	(17)	(7,806)
Distributions to other noncontrolling interests	(53)						(53)
Dividends paid on common stock at $2.93, $2.24 and $1.81 per share for the years ending December 31, 2016, 2015 and 2014, respectively	(210,091)										(210,091)
Balance, end of period at Dec. 31, 2014	1,911,983	14,809	41,903	10,730	13,710	92,422	984	$ 1,163	1,995,484	(1,484)	(257,738)
Balance, end of period (in shares) at Dec. 31, 2014								116,360,239
Issuance of common stock upon the exercise of options	$ 1,542							$ 1	1,541
Issuance of common stock upon the exercise of options (in shares)	79,974							79,974
Restricted stock grants issued	$ 2							$ 2
Restricted stock grants issued (in shares)								174,558
Restricted stock grants cancelled (in shares)								(18,090)
Compensation expense related to stock-based awards	6,055								6,055
Issuance of Operating Partnership units in conjunction with acquisitions	142,399					142,399
Redemption of Operating Partnership units for common stock						(28,106)		$ 8	28,098
Redemption of Operating Partnership units for common stock (in shares)								787,850
Purchase of remaining equity interest in existing consolidated joint venture	(1,268)						(822)		(446)
Issuance of common stock, net of offering costs	446,877							$ 67	446,810
Issuance of common stock, net of offering costs (in shares)								6,735,000
Issuance of 2015 exchangeable senior notes - equity component	22,597								22,597
Repurchase of equity portion of 2013 exchangeable senior notes	(70,112)								(70,112)
Net income	209,536	6,445	2,514	2,074	685	8,344					189,474
Other comprehensive income (loss)	(4,929)	(15)				(46)				(4,868)
Tax effect from vesting of restricted stock grants and stock option exercises	1,727								1,727
Distributions to Operating Partnership units held by noncontrolling interests	(24,503)	(7,050)	(2,515)	(2,074)	(685)	(12,179)
Dividends paid on common stock at $2.93, $2.24 and $1.81 per share for the years ending December 31, 2016, 2015 and 2014, respectively	(269,302)										(269,302)
Balance, end of period at Dec. 31, 2015	$ 2,372,604	14,189	41,902	10,730	13,710	202,834	162	$ 1,241	2,431,754	(6,352)	(337,566)
Balance, end of period (in shares) at Dec. 31, 2015	124,119,531							124,119,531
Issuance of common stock upon the exercise of options	$ 1,444							$ 0	1,444
Issuance of common stock upon the exercise of options (in shares)	97,855							97,855
Restricted stock grants issued	$ 2							$ 2
Restricted stock grants issued (in shares)								119,931
Restricted stock grants cancelled (in shares)								(9,947)
Compensation expense related to stock-based awards	8,045								8,045
Issuance of Operating Partnership units in conjunction with acquisitions	7,247					7,247
Redemption of Operating Partnership units for sale of property	(7,689)					(7,689)
Issuance of Preferred D Units in the Operating Partnership in conjunction with acquisitions														$ 67,193
Redemption of Operating Partnership units for common stock	(506)					(1,083)			577
Redemption of Operating Partnership units for common stock (in shares)								23,850
Purchase of remaining equity interest in existing consolidated joint venture	0					800	(162)		(638)
Issuance of common stock, net of offering costs	123,422							$ 14	123,408
Issuance of common stock, net of offering costs (in shares)								1,381,300
Repurchase of equity portion of 2013 exchangeable senior notes	(872)							$ 2	(874)
Repurchase of equity portion of 2013 exchangeable senior notes (in shares)								148,940
Net income	397,089	7,645	2,514	2,570	1,971	16,262	0				366,127
Other comprehensive income (loss)	24,598	201				1,275				23,122
Tax effect from vesting of restricted stock grants and stock option exercises	2,404								2,404
Distributions to Operating Partnership units held by noncontrolling interests	(30,997)	(7,650)	(2,514)	(2,570)	(1,971)	(16,292)
Dividends paid on common stock at $2.93, $2.24 and $1.81 per share for the years ending December 31, 2016, 2015 and 2014, respectively	(367,818)										(367,818)
Balance, end of period at Dec. 31, 2016	$ 2,596,166	$ 14,385	$ 41,902	$ 10,730	$ 80,903	$ 203,354	$ 0	$ 1,259	$ 2,566,120	$ 16,770	$ (339,257)
Balance, end of period (in shares) at Dec. 31, 2016	125,881,460							125,881,460