CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid in Capital	(Accumulated Deficit) Retained Earnings	Other Comprehensive (Loss) Income
Beginning balance (in shares) at Dec. 31, 2016		29,974,239
Beginning balance at Dec. 31, 2016	$ 328,516	$ 0	$ 364,815	$ (36,296)	$ (3)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Capital contributions	2,997		2,997
Proceeds from initial public offering, net (in shares)		12,800,000
Proceeds from initial public offering, net	163,952	$ 13	163,939
Tax receivable agreement	(203,837)		(203,837)
Stock-based compensation (in shares)		91,168
Stock-based compensation	2,199		2,199
Other comprehensive income	2,357				2,357
Net (loss) income	82,480			82,480
Ending balance (in shares) at Dec. 31, 2017		42,865,407
Ending balance at Dec. 31, 2017	378,664	$ 13	330,113	46,184	2,354
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Change in accounting standard - income taxes				186	(186)
Stock-based compensation	2,278		2,278
Tax withholding payment related to net share settlement of equity awards (in shares)		41,919
Tax withholding payment related to net share settlement of equity awards	(61)		(61)
Other comprehensive income	(2,349)				(2,349)
Net (loss) income	(12,183)			(12,183)
Ending balance (in shares) at Dec. 31, 2018		42,907,326
Ending balance at Dec. 31, 2018	$ 366,349	$ 13	$ 332,330	$ 34,187	$ (181)