Combined Consolidated Statements of Changes in Equity/Capital - USD ($) $ in Thousands	Total	Additional Paid-in-Capital	Retained Earnings	Accumulated Other Comprehensive Income	Noncontrolling Interests Operating Partnership	Noncontrolling Interests Consolidated Joint Ventures	Class A Common Stock Common Stock	Class B Common Stock Common Stock	Preferred Units Series A preferred units	Preferred Units Series B Preferred Units	Common Units	LP Units
Beginning Balance at Dec. 31, 2013									$ 825,985	$ 290,847	$ 59,565
Increase (Decrease) in Partners' Capital
Contributions	$ 1,841					$ 1,841
Distributions	(50,502)				$ (47,926)	(2,207)				(369)
Ending Balance at Dec. 31, 2014									0	0	0
Beginning Balance at Dec. 31, 2013	1,185,234	$ 0	$ 0	$ 0	0	8,837	$ 0
Beginning Balance (in shares) at Dec. 31, 2013							0	0
Increase Decrease in Stockholders' Equity
Equity based compensation	14,451	332			13,829					290
Issuance of common stock (IPO)	259,037	259,021					$ 16
Issuance of common stock (IPO) (in shares)							16,925,000
Shares acquired to satisfy minimum required federal and state tax withholding on vesting restricted stock	(125)				(125)
Shares acquired to satisfy minimum required federal and state tax withholding on vesting restricted stock								(10,000)
Forfeitures (in shares)							(40,000)	(6,000)
Offering costs	(20,523)	(20,523)
Reorganization transactions (in shares)									(828,577)	(291,680)	(60,441)	$ 1,180,698
Exchange of capital for common stock		468,694		14,874			$ 34					(483,602)
Exchange of capital for common stock (in shares)							33,673,000
Exchange of predecessor LP Units for common stock					697,096							$ (697,096)
Exchange of predecessor LP Units for common stock (in shares)								48,537,000
Exchange of noncontrolling interest for common stock		12,502		324	(12,827)		$ 1
Exchange of noncontrolling interest for common stock (in shares)							874,374	(874,374)
Adjustment to tax receivable agreement as a result of the exchange of Class B shares	152	152
Net income (loss)	97,626		44,187		66,437	(370)			(7,471)	(2,631)	(2,526)
Other comprehensive income (loss)	18,016			488	520				$ 10,063	$ 3,543	$ 3,402
Rebalancing of ownership percentage between Company and Operating Partnership		5,360		(30)	(5,330)
Ending Balance (in shares) at Dec. 31, 2014							51,432,000	47,647,000
Ending Balance at Dec. 31, 2014	1,505,207	725,538	44,187	15,656	711,674	8,101	$ 51
Increase (Decrease) in Partners' Capital
Contributions	74					74
Distributions	(56,863)				(56,274)	(589)
Increase Decrease in Stockholders' Equity
Amendment of the par value of the Class B shares from no par value per share to $0.001 per share					(47)			$ 47
Equity based compensation	11,342	308			11,034
Grants of restricted stock		(1)					$ 1
Grants of restricted stock (in shares)							726,000
Shares acquired to satisfy minimum required federal and state tax withholding on vesting restricted stock	(4,885)	(4,817)			(68)
Shares acquired to satisfy minimum required federal and state tax withholding on vesting restricted stock							(262,000)	(4,000)
Forfeitures (in shares)							(188,000)	0
Dividends declared	(41,314)		(41,314)
Exchange of noncontrolling interest for common stock	0	50,449		620	(51,069)		$ 3	$ (3)
Exchange of noncontrolling interest for common stock (in shares)							3,415,389	(3,415,389)
Adjustment to tax receivable agreement as a result of the exchange of Class B shares	242	242
Net income (loss)	89,458		46,698		43,338	(578)
Other comprehensive income (loss)	(4,119)			(2,027)	(2,092)
Rebalancing of ownership percentage between Company and Operating Partnership	0	(5,203)		194	5,009
Ending Balance (in shares) at Sep. 30, 2015							55,123,000	44,228,000
Ending Balance at Sep. 30, 2015	$ 1,499,142	$ 766,516	$ 49,571	$ 14,443	$ 661,505	$ 7,008	$ 55	$ 44