Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Class A Common Stock	Class B Common Stock	Total Stockholders' Equity	Common Stock Class A Common Stock	Common Stock Class B Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Non-controlling Interests	Private Perpetual Preferred Units
Beginning balance (in shares) at Dec. 31, 2015					118,903,000	1,120,000
Beginning balance at Dec. 31, 2015	$ 1,372,686			$ 524,729	$ 1,189	$ 11	$ 469,152	$ (883)	$ 55,260	$ 839,953	$ 8,004
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Class A shares, net of costs (in shares)					29,610,854
Issuance of Class A shares, net of costs	611,206			611,206	$ 296		610,910
Conversion of operating partnership units and Class B shares to Class A shares (in shares)					6,191,000	(24,000)
Conversion of operating partnership units and Class B shares to Class A shares	0			23,678	$ 62		24,044	(428)		(23,678)
Equity compensation:
LTIP Units, net of forfeitures	9,372									9,372
Restricted stock, net of forfeitures (in shares)					40,000
Restricted stock, net of forfeitures	357			357			357
Dividends and distributions	(114,954)			(55,812)					(55,812)	(58,206)	(936)
Net income	107,250			51,456					51,456	54,858	936
Other comprehensive income (loss)	(3,054)			(1,478)				(1,478)		(1,576)
Ending balance (in shares) at Dec. 31, 2016					154,745,000	1,096,000
Ending balance at Dec. 31, 2016	1,982,863			1,154,136	$ 1,547	$ 11	1,104,463	(2,789)	50,904	820,723	8,004
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of operating partnership units and Class B shares to Class A shares (in shares)					5,659,000	(44,000)
Conversion of operating partnership units and Class B shares to Class A shares	0			23,435	$ 57		23,529	(151)		(23,435)
Equity compensation:
LTIP Units, net of forfeitures	13,632									13,632
Restricted stock, net of forfeitures (in shares)					21,000
Restricted stock, net of forfeitures	468			468			468
Dividends and distributions	(126,963)			(66,789)					(66,789)	(59,238)	(936)
Net income	118,253			62,647					62,647	54,670	936
Other comprehensive income (loss)	(10,516)			(5,615)				(5,615)		(4,901)
Ending balance (in shares) at Dec. 31, 2017		160,424,575	1,052,469		160,425,000	1,052,000
Ending balance at Dec. 31, 2017	1,977,737			1,168,282	$ 1,604	$ 11	1,128,460	(8,555)	46,762	801,451	8,004
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Class A shares, net of costs (in shares)					284,000
Issuance of Class A shares, net of costs	4,749			4,749	$ 3		4,746
Conversion of operating partnership units and Class B shares to Class A shares (in shares)					13,141,000	(14,000)
Conversion of operating partnership units and Class B shares to Class A shares	0			70,779	$ 132	$ (1)	70,452	196		(70,779)
Equity compensation:
LTIP Units, net of forfeitures	18,368									18,368
Restricted stock, net of forfeitures (in shares)					24,000
Restricted stock, net of forfeitures	417			417			417
Dividends and distributions	(126,539)			(70,854)					(70,854)	(54,749)	(936)
Net income	117,253			65,603					65,603	50,714	936
Other comprehensive income (loss)	(876)			(494)				(494)		(382)
Ending balance (in shares) at Dec. 31, 2018		173,872,536	1,038,090		173,874,000	1,038,000
Ending balance at Dec. 31, 2018	$ 1,991,109			$ 1,238,482	$ 1,739	$ 10	$ 1,204,075	$ (8,853)	$ 41,511	$ 744,623	$ 8,004