CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Preferred Stock	Paid-in Capital	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Income (Loss)
Balance as of beginning of period (in shares) at Dec. 31, 2016		14,992
Balance as of beginning of period at Dec. 31, 2016	$ 185,548	$ 150	$ 0	$ 190,621	$ (5,296)	$ 73
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	32,662				32,662
Share-based compensation				3,809
Restricted stock unit vesting (in shares)		27
Restricted stock unit vesting	(351)			(351)
Other	29			(44)	0	73
Balance as of end of period (in shares) at Dec. 31, 2017		15,019
Balance as of end of period at Dec. 31, 2017	221,639	$ 150	0	194,123	27,366	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	224,785				224,785
Share-based compensation				4,618
Restricted stock unit vesting (in shares)		61
Restricted stock unit vesting	(1,110)	$ 1		(1,111)
Other	(82)					(82)
Balance as of end of period (in shares) at Dec. 31, 2018		15,080
Balance as of end of period at Dec. 31, 2018	447,355	$ 151	0	197,630	249,492	82
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	70,589				70,589
Share-based compensation				4,082
Restricted stock unit vesting (in shares)		56
Restricted stock unit vesting	(1,046)			(1,046)
Other	141					141
Balance as of end of period (in shares) at Dec. 31, 2019		15,136
Balance as of end of period at Dec. 31, 2019	$ 520,745	$ 151	$ 0	$ 200,666	$ 319,987	$ (59)