CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Total	Total Stockholders' Equity	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss	Noncontrolling Interests
Beginning balance (in shares) at Dec. 31, 2017			140,993,985
Beginning balance at Dec. 31, 2017	$ 3,967,999	$ 3,681,578	$ 1,410	$ 4,510,489	$ (830,279)	$ (42)	$ 286,421
Increase (Decrease) in Stockholders' Equity
Net income	55,726	48,271			48,271		7,455
Interest rate cap/swap agreements	184	184				184
Amortization of share and unit-based plans (in shares)			121,924
Amortization of share and unit-based plans	28,219	28,219	$ 1	28,218
Employee stock purchases (in shares)			17,240
Employee stock purchases	806	806		806
Distributions declared	(313,342)	(313,342)			(313,342)
Distributions to noncontrolling interests	(26,101)						(26,101)
Contributions from noncontrolling interests	16						16
Conversion of noncontrolling interests to common shares (in shares)			66,711
Conversion of noncontrolling interests to common shares	0	75	$ 1	74			(75)
Redemption of noncontrolling interests	(719)	(486)		(486)			(233)
Adjustment of noncontrolling interests in Operating Partnership	0	24,002		24,002			(24,002)
Ending balance (in shares) at Sep. 30, 2018			141,199,860
Ending balance at Sep. 30, 2018	3,287,929	3,044,448	$ 1,412	4,563,103	(1,520,209)	142	243,481
Beginning balance (in shares) at Jun. 30, 2018			141,184,335
Beginning balance at Jun. 30, 2018	3,315,175	3,070,510	$ 1,412	4,558,873	(1,489,742)	(33)	244,665
Increase (Decrease) in Stockholders' Equity
Net income	81,241	74,028			74,028		7,213
Interest rate cap/swap agreements	175	175				175
Amortization of share and unit-based plans (in shares)			3,517
Amortization of share and unit-based plans	4,616	4,616		4,616
Distributions declared	(104,495)	(104,495)			(104,495)
Distributions to noncontrolling interests	(8,203)						(8,203)
Contributions from noncontrolling interests	16						16
Conversion of noncontrolling interests to common shares (in shares)			12,008
Conversion of noncontrolling interests to common shares	0	0	$ 0	0			0
Redemption of noncontrolling interests	(596)	(402)		(402)			(194)
Adjustment of noncontrolling interests in Operating Partnership	0	16		16			(16)
Ending balance (in shares) at Sep. 30, 2018			141,199,860
Ending balance at Sep. 30, 2018	$ 3,287,929	3,044,448	$ 1,412	4,563,103	(1,520,209)	142	243,481
Beginning balance (in shares) at Dec. 31, 2018	141,221,712		141,221,712
Beginning balance at Dec. 31, 2018	$ 3,188,432	2,950,232	$ 1,412	4,567,643	(1,614,357)	(4,466)	238,200
Increase (Decrease) in Stockholders' Equity
Net income	72,815	69,929			69,929		2,886
Interest rate cap/swap agreements	(6,480)	(6,480)				(6,480)
Amortization of share and unit-based plans (in shares)			101,213
Amortization of share and unit-based plans	13,353	13,353	$ 1	13,352
Employee stock purchases (in shares)			26,800
Employee stock purchases	819	819		819
Distributions declared	(318,176)	(318,176)			(318,176)
Distributions to noncontrolling interests	(41,200)						(41,200)
Contributions from noncontrolling interests	460						460
Conversion of noncontrolling interests to common shares (in shares)			21,000
Conversion of noncontrolling interests to common shares	0	1,005		1,005			(1,005)
Redemption of noncontrolling interests	(51)	(26)		(26)			(25)
Adjustment of noncontrolling interests in Operating Partnership	$ 0	(1,242)		(1,242)			1,242
Ending balance (in shares) at Sep. 30, 2019	141,370,725		141,370,725
Ending balance at Sep. 30, 2019	$ 2,907,769	2,707,211	$ 1,413	4,581,551	(1,864,807)	(10,946)	200,558
Beginning balance (in shares) at Jun. 30, 2019			141,364,568
Beginning balance at Jun. 30, 2019	2,969,370	2,764,144	$ 1,413	4,578,620	(1,805,097)	(10,792)	205,226
Increase (Decrease) in Stockholders' Equity
Net income	50,025	46,371			46,371		3,654
Interest rate cap/swap agreements	(154)	(154)				(154)
Amortization of share and unit-based plans (in shares)			6,157
Amortization of share and unit-based plans	3,315	3,315		3,315
Distributions declared	(106,081)	(106,081)			(106,081)
Distributions to noncontrolling interests	(8,742)						(8,742)
Contributions from noncontrolling interests	50						50
Redemption of noncontrolling interests	(14)	(6)		(6)			(8)
Adjustment of noncontrolling interests in Operating Partnership	$ 0	(378)		(378)			378
Ending balance (in shares) at Sep. 30, 2019	141,370,725		141,370,725
Ending balance at Sep. 30, 2019	$ 2,907,769	$ 2,707,211	$ 1,413	$ 4,581,551	$ (1,864,807)	$ (10,946)	$ 200,558