Consolidated Condensed Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Noncontrolling Interest [Member]	Total
Balance (in shares) at Dec. 31, 2014	33,419,000
Balance at Dec. 31, 2014	$ 334	$ 87,370	$ 300,222	$ 387,926
Net income			10,188	10,188	$ 10,188
Issuance of common stock from share-based payment arrangement exercises and vesting of performance unit awards (in shares)	84,000
Issuance of common stock from share-based payment arrangement exercises and vesting of performance unit awards	$ 1	972		973
Tax benefits from share-based payment arrangement exercises		178		178
Share-based payment arrangement compensation expense		273		273
Dividends on common stock			(837)	(837)
Balance (in shares) at Mar. 31, 2015	33,503,000
Balance at Mar. 31, 2015	$ 335	88,793	309,573	398,701
Tax benefits from share-based payment arrangement exercises		178		178
Net income			25,557	25,557
Issuance of common stock from share-based payment arrangement exercises and vesting of performance unit awards (in shares)	198,000
Issuance of common stock from share-based payment arrangement exercises and vesting of performance unit awards	$ 2	2,515		2,517
Tax benefits from share-based payment arrangement exercises		195		195
Share-based payment arrangement compensation expense		1,131		1,131
Dividends on common stock			(2,505)	(2,505)
Balance (in shares) at Dec. 31, 2015	32,760,000
Balance at Dec. 31, 2015	$ 328	76,468	332,625	409,421	409,421
Repurchase and retirement of common stock (in shares)	(941,000)
Repurchase and retirement of common stock	$ (9)	(16,166)		(16,175)
Tax benefits from share-based payment arrangement exercises		195		195
Repurchase and retirement of common stock	$ (9)	(16,166)		(16,175)
Net income			8,193	8,193	8,193
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
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	$ 410,812
Repurchase and retirement of common stock (in shares)	(456,000)				(455,581)
Repurchase and retirement of common stock	$ (5)	(7,508)		(7,513)	$ (7,500)
Repurchase and retirement of common stock	$ (5)	(7,508)		(7,513)	$ (7,500)
Tax deficiencies from share-based payment arrangement exercises		(169)		(169)
Employee taxes paid in exchange for shares withheld		$ (127)		$ (127)