CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Distributions in Excess of Earnings [Member]	Total Stockholders' Equity [Member]	Noncontrolling Interests [Member]
Beginning balance (in shares) at Dec. 31, 2017		98,620,333
Beginning balance at Dec. 31, 2017	$ 3,960,316	$ 986	$ 3,822,492	$ (122,685)	$ 3,700,793	$ 259,523
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	40,971			36,246	36,246	4,725
Issuance of share-based compensation awards	1,864		1,864		1,864
Non-cash amortization of share-based compensation	5,094		5,094		5,094
Settlement of restricted stock units for shares of common stock (in shares)		405,067
Settlement of restricted stock units for shares of common stock	0	$ 4	(4)
Repurchase and cancellation of common stock, stock options, and restricted stock units (in shares)		(192,195)
Repurchase and cancellation of common stock, stock options, and restricted stock units	(13,642)	$ (2)	(13,640)		(13,642)
Exchange of common units of the Operating Partnership (in shares)		6,503
Exchange of common units of the Operating Partnership	0		244		244	(244)
Distributions to noncontrolling interests in consolidated property partnerships	(2,177)					(2,177)
Adjustment for noncontrolling interest	0		335		335	(335)
Dividends declared per common share and common unit ($0.485 and $0.455 per share/unit for the three months ended June 30, 2019 and 2018, and $0.455 and $0.425 per share/unit for the three months ended March 31, 2019, respectively)	(44,954)			(44,075)	(44,075)	(879)
Ending balance (in shares) at Mar. 31, 2018		98,839,708
Ending balance at Mar. 31, 2018	3,947,472	$ 988	3,816,385	(130,514)	3,686,859	260,613
Beginning balance (in shares) at Dec. 31, 2017		98,620,333
Beginning balance at Dec. 31, 2017	3,960,316	$ 986	3,822,492	(122,685)	3,700,793	259,523
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	72,726
Ending balance (in shares) at Jun. 30, 2018		100,559,903
Ending balance at Jun. 30, 2018	4,063,873	$ 1,006	3,951,289	(149,368)	3,802,927	260,946
Beginning balance (in shares) at Mar. 31, 2018		98,839,708
Beginning balance at Mar. 31, 2018	3,947,472	$ 988	3,816,385	(130,514)	3,686,859	260,613
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	31,755			27,549	27,549	4,206
Issuance of common stock (in shares)		1,719,195
Issuance of common stock	124,147	$ 17	124,130		124,147
Issuance of share-based compensation awards	589		589		589
Non-cash amortization of share-based compensation	11,503		11,503		11,503
Exercise of stock options (in shares)		1,000
Exercise of stock options	41		41		41
Exchange of common units of the Operating Partnership	0	$ 1			1	(1)
Distributions to noncontrolling interests in consolidated property partnerships	(4,288)					(4,288)
Adjustment for noncontrolling interest	0		(1,359)		(1,359)	1,359
Dividends declared per common share and common unit ($0.485 and $0.455 per share/unit for the three months ended June 30, 2019 and 2018, and $0.455 and $0.425 per share/unit for the three months ended March 31, 2019, respectively)	(47,346)			(46,403)	(46,403)	(943)
Ending balance (in shares) at Jun. 30, 2018		100,559,903
Ending balance at Jun. 30, 2018	$ 4,063,873	$ 1,006	3,951,289	(149,368)	3,802,927	260,946
Beginning balance (in shares) at Dec. 31, 2018	100,746,988	100,746,988
Beginning balance at Dec. 31, 2018	$ 4,201,261	$ 1,007	3,976,953	(48,053)	3,929,907	271,354
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	41,794			36,903	36,903	4,891
Issuance of share-based compensation awards	2,210		2,210		2,210
Non-cash amortization of share-based compensation	8,817		8,817		8,817
Settlement of restricted stock units for shares of common stock (in shares)		393,240
Settlement of restricted stock units for shares of common stock	0	$ 4	(4)
Repurchase and cancellation of common stock, stock options, and restricted stock units (in shares)		(175,204)
Repurchase and cancellation of common stock, stock options, and restricted stock units	(12,130)	$ (1)	(12,129)		(12,130)
Exchange of common units of the Operating Partnership (in shares)		2,000
Exchange of common units of the Operating Partnership	0		78		78	(78)
Distributions to noncontrolling interests in consolidated property partnerships	(6,309)					(6,309)
Adjustment for noncontrolling interest	0		279		279	(279)
Dividends declared per common share and common unit ($0.485 and $0.455 per share/unit for the three months ended June 30, 2019 and 2018, and $0.455 and $0.425 per share/unit for the three months ended March 31, 2019, respectively)	(49,315)			(48,394)	(48,394)	(921)
Ending balance (in shares) at Mar. 31, 2019		100,967,024
Ending balance at Mar. 31, 2019	$ 4,183,182	$ 1,010	3,976,204	(62,690)	3,914,524	268,658
Beginning balance (in shares) at Dec. 31, 2018	100,746,988	100,746,988
Beginning balance at Dec. 31, 2018	$ 4,201,261	$ 1,007	3,976,953	(48,053)	3,929,907	271,354
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 89,009
Ending balance (in shares) at Jun. 30, 2019	100,972,035	100,972,035
Ending balance at Jun. 30, 2019	$ 4,186,903	$ 1,010	3,984,867	(70,345)	3,915,532	271,371
Beginning balance (in shares) at Mar. 31, 2019		100,967,024
Beginning balance at Mar. 31, 2019	4,183,182	$ 1,010	3,976,204	(62,690)	3,914,524	268,658
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	47,215			42,194	42,194	5,021
Issuance of share-based compensation awards	820		820		820
Non-cash amortization of share-based compensation	8,732		8,732		8,732
Exercise of stock options (in shares)		1,500
Exercise of stock options	64		64		64
Settlement of restricted stock units for shares of common stock (in shares)		16,270
Settlement of restricted stock units for shares of common stock	0
Repurchase and cancellation of common stock, stock options, and restricted stock units (in shares)		(12,759)
Repurchase and cancellation of common stock, stock options, and restricted stock units	(793)		(793)		(793)
Distributions to noncontrolling interests in consolidated property partnerships	(1,487)					(1,487)
Adjustment for noncontrolling interest	0		(160)		(160)	160
Dividends declared per common share and common unit ($0.485 and $0.455 per share/unit for the three months ended June 30, 2019 and 2018, and $0.455 and $0.425 per share/unit for the three months ended March 31, 2019, respectively)	$ (50,830)			(49,849)	(49,849)	(981)
Ending balance (in shares) at Jun. 30, 2019	100,972,035	100,972,035
Ending balance at Jun. 30, 2019	$ 4,186,903	$ 1,010	$ 3,984,867	$ (70,345)	$ 3,915,532	$ 271,371