Earnings per Share (Details) (USD $) In Thousands, except Per Share data	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Net income (loss)	$ 16,803	$ 8,273	$ 72,450	$ 11,871
Shares used in computing basic earnings per share	42,511	41,774	42,334	40,939
Dilutive common stock equivalents	284	460	381	578
Shares used in computing diluted earnings per share	42,795	42,234	42,715	41,517
Basic earnings per share	$ 0.40	$ 0.20	$ 1.71	$ 0.29
Diluted earnings per share	$ 0.39	$ 0.20	$ 1.70	$ 0.29