Earnings Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Earnings Per Share Reconciliation [Abstract]
Weighted average number of common shares outstanding used in computing basic earnings per share	45,460	44,820
Net income attributable to common stockholders	$ 4,871	$ 19,684
Earnings per share attributable to common stockholders - basic	$ 0.11	$ 0.44
Weighted average number of common shares outstanding used in computing basic earnings per share	45,460	44,820
Add: Assumed exercise of stock options and stock awards	1,475	1,860
Diluted shares	46,935	46,680
Net income attributable to common stockholders	$ 4,871	$ 19,684
Earnings per share attributable to common stockholders - diluted	$ 0.10	$ 0.42