Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning balance at Dec. 31, 2016	$ 283,348	$ 27	$ 168,299	$ 191,108	$ (76,086)
Beginning balance (in shares) at Dec. 31, 2016		27,206
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation and vesting of restricted stock	2,765		2,765
Stock-based compensation and vesting of restricted stock (in shares)		42
Net income	25,710			25,710
Conversion of convertible debt	51,851	$ 2	51,849
Conversion of Convertible Debt (in shares)		1,748
Dividends declared	(9,379)			(9,379)
Change in fair value of Derivative Financial Instruments, net of tax	657				657
Cumulative foreign currency translation adjustment	13,827				13,827
Ending balance at Jun. 30, 2017	368,779	$ 29	222,913	207,439	(61,602)
Ending balance (in shares) at Jun. 30, 2017		28,996
Beginning balance at Dec. 31, 2017	396,705	$ 29	223,336	223,204	(49,864)
Beginning balance (in shares) at Dec. 31, 2017		29,058
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation and vesting of restricted stock	1,190		1,190
Stock-based compensation and vesting of restricted stock (in shares)		50
Net income	28,008			28,008
Dividends declared	(9,963)			(9,963)
Change in fair value of Derivative Financial Instruments, net of tax	1,078				1,078
Minimum Pension adjustment, net of tax	4,392				4,392
Cumulative foreign currency translation adjustment	(8,518)				(8,518)
Ending balance at Jun. 30, 2018	$ 412,892	$ 29	$ 224,526	$ 241,249	$ (52,912)
Ending balance (in shares) at Jun. 30, 2018		29,108