Condensed Consolidated Statement of Changes in Stockholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Noncontrolling Interest
Balance at Dec. 31, 2011	$ 1,374,079	$ 863	$ 644,174	$ 557,055	$ 171,987
Balance, shares at Dec. 31, 2011	86,572,098	86,572,098
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	5,784			6,829	(1,045)
Comprehensive income attributable to noncontrolling interest	2,467				2,467
Stock options exercised, value	117	0	117
Stock options exercised, shares		16,835
Tax effect from share-based compensation arrangements	(300)		(300)
Share-based compensation costs	5,953		5,953
Balance at Jun. 30, 2012	$ 1,388,100	$ 863	$ 649,944	$ 563,884	$ 173,409
Balance, shares at Jun. 30, 2012	86,588,933	86,588,933