Consolidated Condensed Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Total
Balance (in shares) at Dec. 31, 2015	32,760,000
Balance at Dec. 31, 2015	$ 328	$ 76,468	$ 332,625	$ 409,421
Net income			8,193	$ 8,193
Repurchase and retirement of common stock (in shares)	(456,000)			(455,581)
Repurchase and retirement of common stock	$ (5)	(7,508)		$ (7,513)
Issuance of common stock from share-based payment arrangement exercises and vesting of performance unit awards (in shares)	115,000
Issuance of common stock from share-based payment arrangement exercises and vesting of performance unit awards	$ 1	1,527		1,528
Tax deficiencies from share-based payment arrangement exercises		(169)		(169)
Employee taxes paid in exchange for shares withheld		(127)		(127)
Share-based payment arrangement compensation expense		290		290
Dividends on common stock			(811)	(811)
Balance (in shares) at Mar. 31, 2016	32,419,000
Balance at Mar. 31, 2016	$ 324	70,481	340,007	410,812
Net income			25,271	$ 25,271
Repurchase and retirement of common stock (in shares)				0
Issuance of common stock from share-based payment arrangement exercises and vesting of performance unit awards (in shares)	216,000
Issuance of common stock from share-based payment arrangement exercises and vesting of performance unit awards	$ 2	2,886		$ 2,888
Share-based payment arrangement compensation expense		593		593
Dividends on common stock			(2,441)	(2,441)
Balance (in shares) at Dec. 31, 2016	32,635,000
Balance at Dec. 31, 2016	$ 326	74,175	362,837	437,338
Tax benefits from share-based payment arrangement exercises		215		215
Net income			8,214	$ 8,214
Repurchase and retirement of common stock (in shares)				0
Issuance of common stock from share-based payment arrangement exercises and vesting of performance unit awards (in shares)	50,000
Issuance of common stock from share-based payment arrangement exercises and vesting of performance unit awards	$ 1	614		$ 615
Employee taxes paid in exchange for shares withheld		(47)		(47)
Share-based payment arrangement compensation expense		149		149
Dividends on common stock			(817)	(817)
Balance (in shares) at Mar. 31, 2017	32,685,000
Balance at Mar. 31, 2017	$ 327	$ 74,891	$ 370,234	$ 445,452