Condensed Consolidated Statements of Equity (USD $) In Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock, at Cost	Non- controlling Interests
Balance at Dec. 31, 2010	$ 151,898	$ 25,413	$ 79,297	$ 58,546	$ (14,418)	$ 3,060
Balance, shares at Dec. 31, 2010		25,413
Net income	16,124			14,825		1,299
Contributions from non-controlling interest holders	6					6
Distributions to non-controlling interest holders	(2,824)					(2,824)
Share-based compensation expense	788		788
Exercise of stock options	441			(1,417)	1,858
Repurchase of shares	(7,238)				(7,238)
Balance at Mar. 31, 2011	159,195	25,413	80,085	71,954	(19,798)	1,541
Balance, shares at Mar. 31, 2011		25,413
Balance at Dec. 31, 2011	165,943	25,413	83,229	126,161	(72,048)	3,188
Balance, shares at Dec. 31, 2011		25,413
Net income	27,121			25,229		1,892
Contributions from non-controlling interest holders	11					11
Distributions to non-controlling interest holders	(2,083)					(2,083)
Share-based compensation expense	(184)		(184)
Exercise of stock options	1,977			(4,364)	6,341
Repurchase of shares	(16,781)				(16,781)
Balance at Mar. 31, 2012	$ 176,004	$ 25,413	$ 83,045	$ 147,026	$ (82,488)	$ 3,008
Balance, shares at Mar. 31, 2012		25,413