Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Noncontrolling Interest [Member]	Total
Balance (in shares) at Dec. 31, 2012	33,164
Balance at Dec. 31, 2012	$ 332	$ 82,679	$ 246,349	$ 2,563	$ 331,923
Net income			30,147		30,147
Issuance of common stock from share-based payment arrangement exercises and vesting of performance unit awards (in shares)	137
Issuance of common stock from share-based payment arrangement exercises and vesting of performance unit awards	$ 1	1,125			1,126
Tax benefits from share-based payment arrangement exercises		189			189
Share-based payment arrangement compensation expense		1,084			1,084
Dividends on common stock			(2,769)		(2,769)
Income before income taxes attributable to noncontrolling interest				84	84
Noncontrolling interest distributions				(84)	(84)
Change to equity method of accounting				$ (2,563)	(2,563)
Balance (in shares) at Dec. 31, 2013	33,301
Balance at Dec. 31, 2013	$ 333	85,077	273,727		359,137
Tax benefits from share-based payment arrangement exercises		189			189
Net income			29,834		29,834
Issuance of common stock from share-based payment arrangement exercises and vesting of performance unit awards (in shares)	118
Issuance of common stock from share-based payment arrangement exercises and vesting of performance unit awards	$ 1	1,213			1,214
Tax benefits from share-based payment arrangement exercises		159			159
Share-based payment arrangement compensation expense		921			921
Dividends on common stock			(3,339)		$ (3,339)
Income before income taxes attributable to noncontrolling interest
Balance (in shares) at Dec. 31, 2014	33,419
Balance at Dec. 31, 2014	$ 334	87,370	300,222		$ 387,926
Tax benefits from share-based payment arrangement exercises		159			159
Net income			35,745		35,745
Issuance of common stock from share-based payment arrangement exercises and vesting of performance unit awards (in shares)	282
Issuance of common stock from share-based payment arrangement exercises and vesting of performance unit awards	$ 3	3,487			3,490
Tax benefits from share-based payment arrangement exercises		373			373
Share-based payment arrangement compensation expense		1,404			1,404
Dividends on common stock			(3,342)		$ (3,342)
Income before income taxes attributable to noncontrolling interest
Balance (in shares) at Dec. 31, 2015	32,760
Balance at Dec. 31, 2015	$ 328	76,468	$ 332,625		$ 409,421
Tax benefits from share-based payment arrangement exercises		373			373
Repurchase and retirement of common stock (in shares)	(941)
Repurchase and retirement of common stock	$ (9)	(16,166)			16,175
Repurchase and retirement of common stock	$ 9	$ 16,166			$ (16,175)