CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (unaudited) Statement - USD ($) $ in Thousands	Total	Additional Paid-in capital	Retained Earnings	Noncontrolling Interest	Class A common stock	Class A common stock Common stock	Class B common stock	Class B common stock Common stock
Members' equity, beginning balance at Dec. 31, 2016	$ (123,510)	$ (283,529)	$ 160,019
Increase (Decrease) in Stockholders' Equity
Net income	60,604		60,604
Share-based compensation prior to Reorganization Transactions	1,574	1,574
Distributions prior to Reorganization Transactions	(55,283)		(55,283)
Equity-based payments to non-employees	198	198
Class A stock option exercises (in shares)					2,000
Class A common stock option exercises in connection with IPO	15	15
Members' equity, ending balance at Jun. 30, 2017	(116,402)	(281,742)	165,340
Redeemable preferred units at Dec. 31, 2016	335,720
Redeemable preferred units at Jun. 30, 2017	335,720
Beginning Balance at Dec. 31, 2016	212,210
Ending Balance at Jun. 30, 2017	219,318
Members' equity, beginning balance at Dec. 31, 2017	(456,387)	(554,906)	98,519
Beginning balance (in shares) at Dec. 31, 2017					0		0
Increase (Decrease) in Stockholders' Equity
Net income	59,420
Ending balance (in shares) at Jun. 30, 2018					57,650,251	57,650,251	128,983,353	128,983,353.000
Ending balance at Jun. 30, 2018	(46,460)	$ 15,373	$ 5,482	$ (68,020)		$ 576		$ 129
Redeemable preferred units at Dec. 31, 2017	430,348
Redeemable preferred units at Jun. 30, 2018	0
Beginning Balance at Dec. 31, 2017	$ (26,039)