CONDENSED CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings (Accumulated Deficit)	Accumulated Other Comprehensive Income (Loss)
Balance (in shares) at Dec. 31, 2015		91,428,274
Balance at Dec. 31, 2015	$ 545,504	$ 914	$ 679,916	$ (49,523)	$ (85,803)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, net of tax impact of share-based compensation (in shares)		354,443
Issuance of common stock, net of tax impact of share-based compensation	(1,952)	$ 4	(1,956)
Share-based compensation expense	4,276		4,276
Repurchase of common stock (in shares)		(1,371,185)
Repurchase of common stock	(25,000)	$ (14)	(24,986)
Net income	72,572			72,572
Dividends	(16,673)		(8,390)	(8,283)
Other comprehensive income (loss):
Cumulative translation adjustment	(1,055)				(1,055)
Pension and other postretirement benefit liability adjustment, net of tax	3,035				3,035
Balance (in shares) at Jun. 30, 2016		90,411,532.000
Balance at Jun. 30, 2016	$ 580,707	$ 904	648,860	14,766	(83,823)
Balance (in shares) at Dec. 31, 2016	90,586,741	90,586,741
Balance at Dec. 31, 2016	$ 610,556	$ 906	653,629	45,654	(89,633)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)		326,823
Issuance of common stock	(880)	$ 3	(883)
Share-based compensation expense	3,975		3,975
Repurchase of common stock (in shares)		0
Net income	7,888			7,888
Dividends	(16,604)			(16,604)
Other comprehensive income (loss):
Cumulative translation adjustment	0
Pension and other postretirement benefit liability adjustment, net of tax	$ 3,276				3,276
Balance (in shares) at Jun. 30, 2017	90,913,564	90,913,564
Balance at Jun. 30, 2017	$ 608,211	$ 909	$ 656,721	$ 36,938	$ (86,357)