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 at Dec. 31, 2011	$ 330	$ 80,078	$ 237,762	$ 2,189	$ 320,359
Balance (in Shares) at Dec. 31, 2011	32,977
Net income			13,030		13,030
Issuance of common stock from share-based payment arrangement exercises and vesting of performance unit awards	1	615			616
Issuance of common stock from share-based payment arrangement exercises and vesting of performance unit awards (in Shares)	130
Tax benefits from share-based payment arrangement exercises		350			350
Share-based payment arrangement compensation expense		791			791
Dividends on common stock			(993)		(993)
Income before income taxes attributable to noncontrolling interest				406	406
Noncontrolling interest distributions				(185)	(185)
Balance at Jun. 30, 2012	331	81,834	249,799	2,410	334,374
Balance (in Shares) at Jun. 30, 2012	33,107
Net income			14,237		14,237
Issuance of common stock from share-based payment arrangement exercises and vesting of performance unit awards	1	352	(1)		352
Issuance of common stock from share-based payment arrangement exercises and vesting of performance unit awards (in Shares)	57
Tax benefits from share-based payment arrangement exercises		59			59
Share-based payment arrangement compensation expense		434			434
Dividends on common stock			(17,686)		(17,686)
Income before income taxes attributable to noncontrolling interest				91	91
Noncontrolling interest distributions				62	62
Balance at Dec. 31, 2012	332	82,679	246,349	2,563	331,923
Balance (in Shares) at Dec. 31, 2012	33,164
Net income			14,869		14,869
Issuance of common stock from share-based payment arrangement exercises and vesting of performance unit awards		179			179
Issuance of common stock from share-based payment arrangement exercises and vesting of performance unit awards (in Shares)	57
Tax benefits from share-based payment arrangement exercises		143			143
Share-based payment arrangement compensation expense		651			651
Dividends on common stock			(1,107)		(1,107)
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 at Jun. 30, 2013	$ 332	$ 83,652	$ 260,111		$ 344,095
Balance (in Shares) at Jun. 30, 2013	33,221