Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Statement of Other Comprehensive Income [Abstract]
Net income	$ 17,152	$ 226,126	$ 160,853
Other comprehensive income (loss):
Foreign currency translation adjustments	1,357	24	0
Change in unrealized gains on available-for-sale securities	1,394	(111)	798
Other comprehensive income (loss) before tax	2,751	(87)	798
Income tax expense related to items of other comprehensive income	(538)	43	(321)
Other comprehensive income (loss), net of tax	2,213	(44)	477
Comprehensive income	$ 19,365	$ 226,082	$ 161,330