CONDENSED CONSOLIDATED STATEMENTS OF EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common stock	Additional paid-in capital	Retained earnings	Treasury stock, at cost	Non-controlling interests
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	137,993			136,019		1,974
Distributions to non-controlling interest holders	(1,813)					(1,813)
Share-based compensation expense	1,638		1,638
Exercise of stock options	2,523			(5,628)	8,151
Repurchase of shares	(208,820)				(208,820)
Balance at Sep. 30, 2014	89,262	$ 25,413	90,911	369,952	(398,217)	1,203
Balance (in shares) at Sep. 30, 2014		25,413
Balance at Dec. 31, 2014	41,443	$ 25,413	91,509	367,967	(444,495)	1,049
Balance (in shares) at Dec. 31, 2014		25,413
Increase (Decrease) in Equity
Net income	89,151			86,694		2,457
Distributions to non-controlling interest holders	(2,144)					(2,144)
Share-based compensation expense	3,258		3,258
Exercise of stock options	332			(2,054)	2,386
Stock Issued During Period, Value, Acquisitions				(21,612)	36,039
Value of common stock paid at acquisition	14,427			14,427
Repurchase of shares	(48,971)				(48,971)
Balance at Sep. 30, 2015	$ 97,496	$ 25,413	$ 94,767	$ 430,995	$ (455,041)	$ 1,362
Balance (in shares) at Sep. 30, 2015		25,413