Condensed Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock	Paid-in Capital	Retained Earnings	Treasury Stock, at cost	Accumulated Other Comprehensive Income
Beginning Balance at Dec. 31, 2017	$ 665,865	$ 250	$ 700,125	$ 247,232	$ (302,109)	$ 20,367
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends on common shares ($0.45/share)	(8,553)			(8,553)
Total comprehensive income	65,884			59,985		5,899
Employee stock-based compensation	3,845		3,845
Purchase of common stock under share repurchase program	(38,589)				(38,589)
Warrants exercised	10		10
Ending Balance at Mar. 31, 2018	688,462	250	703,980	298,664	(340,698)	26,266
Beginning Balance at Dec. 31, 2018	704,821	250	717,492	527,666	(583,883)	43,296
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends on common shares ($0.45/share)	(8,111)			(8,111)
Total comprehensive income	75,835			72,741		3,094
Employee stock-based compensation	5,651		5,651
Purchase of common stock under share repurchase program	(78,249)				(78,249)
Ending Balance at Mar. 31, 2019	$ 699,947	$ 250	$ 723,143	$ 592,296	$ (662,132)	$ 46,390