CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Paid-in Capital	Retained Earnings	Non-controlling Interest	Accumulated Other Comprehensive Income
Beginning Balance at Dec. 31, 2014	$ 151,622		$ 165,857	$ (14,425)	$ 103	$ 87
Beginning Balance (in shares) at Dec. 31, 2014		46,426,714
Issuance of restricted stock units	1,488		1,488
Issuance of restricted stock units (in shares)		17,980
Acquisition of non-controlling interest	3,449		3,552		$ (103)
Acquisition of non-controlling interest (in shares)		373,135
Net income	114,183			114,183
Other comprehensive income	$ (75)					(75)
Exercise of stock options (in shares)	0
Ending Balance at Dec. 31, 2015	$ 270,667		170,897	99,758		12
Ending Balance (in shares) at Dec. 31, 2015		46,817,829
Issuance of restricted stock units	3,341		3,341
Issuance of restricted stock units (in shares)		217,997
Net income	24,802			24,802
Exercise of stock options	$ 385		385
Exercise of stock options (in shares)	132,900	132,900
Shares withheld related to net share settlement of stock awards	$ (744)		(744)
Shares withheld related to net share settlement of stock awards (in shares)		(62,982)
Ending Balance at Dec. 31, 2016	298,451		173,879	124,560		12
Ending Balance (in shares) at Dec. 31, 2016		47,105,744
Isle common stock exchanged at merger	574,811		574,811
Isle common stock exchanged at merger (in shares)		28,468,182
Issuance of restricted stock units	6,322		6,322
Issuance of restricted stock units (in shares)		1,070,552
Net income	73,940			73,940
Other comprehensive income	67					67
Exercise of stock options	$ 2,900		2,900
Exercise of stock options (in shares)	1,185,745	1,185,745
Shares withheld related to net share settlement of stock awards	$ (11,365)		(11,365)
Shares withheld related to net share settlement of stock awards (in shares)		(1,004,257)
Ending Balance at Dec. 31, 2017	$ 945,126		$ 746,547	$ 198,500		$ 79
Ending Balance (in shares) at Dec. 31, 2017		76,825,966