CONDENSED CONSOLIDATED STATEMENTS OF EQUITY (USD $) In Thousands, unless otherwise specified	Total	Common stock	Additional paid-in capital	Retained earnings	Treasury stock, at cost	Non-controlling interests
Balance at Dec. 31, 2012	$ 159,829	$ 25,413	$ 86,873	$ 124,127	$ (77,954)	$ 1,370
Balance (in shares) at Dec. 31, 2012		25,413
Increase (Decrease) in Equity
Net income	28,527			27,518		1,009
Contributions from non-controlling interest holders	12					12
Distributions to non-controlling interest holders	(1,090)					(1,090)
Share-based compensation expense	1,424		1,424
Exercise of stock options	456			(204)	660
Repurchase of shares	(21,997)				(21,997)
Balance at Mar. 31, 2013	167,161	25,413	88,297	151,441	(99,291)	1,301
Balance (in shares) at Mar. 31, 2013		25,413
Balance at Dec. 31, 2013	157,741	25,413	89,273	239,561	(197,548)	1,042
Balance (in shares) at Dec. 31, 2013		25,413
Increase (Decrease) in Equity
Net income	40,146			39,631		515
Distributions to non-controlling interest holders	(653)					(653)
Share-based compensation expense	658		658
Exercise of stock options	401			(1,732)	2,133
Repurchase of shares	(35,766)				(35,766)
Balance at Mar. 31, 2014	$ 162,527	$ 25,413	$ 89,931	$ 277,460	$ (231,181)	$ 904
Balance (in shares) at Mar. 31, 2014		25,413