Consolidated Statement of Stockholders' Equity (Unaudited) - 6 months ended Jun. 30, 2017 - USD ($) $ in Thousands	Dividends Paid to Shareholders [Member] Common Stock [Member]	Dividends Paid to Shareholders [Member] Additional Paid-in Capital [Member]	Dividends Paid to Shareholders [Member] Retained Earnings [Member]	Dividends Paid to Shareholders [Member] Treasury Stock [Member]	Dividends Paid to Shareholders [Member] AOCI Attributable to Parent [Member]	Dividends Paid to Shareholders [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	AOCI Attributable to Parent [Member]	Total
Balance (in shares) at Dec. 31, 2016							5,708,223
Balance at Dec. 31, 2016							$ 59	$ 17,669	$ 511,776	$ (74,547)	$ (446)	$ 454,511
Net income									61,790			61,790
Changes in pension, net of tax											4	4
Equity-based compensation (in shares)
Equity-based compensation								4,845				4,845
Issuance of restricted stock awards, net of forfeitures (in shares)							18,238
Issuance of restricted stock awards, net of forfeitures
Repurchases of common stock (in shares)							(700)					(700)
Repurchases of common stock										(399)		$ (399)
Withholding tax for equity awards (in shares)							(666)					(666)
Withholding tax for equity awards										(438)		$ (438)
Dividends paid to stockholders			$ (17,165)			$ (17,165)
Balance (in shares) at Jun. 30, 2017							5,725,095
Balance at Jun. 30, 2017							$ 59	$ 22,514	$ 556,401	$ (75,384)	$ (442)	$ 503,148