Conslidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Statement of Other Comprehensive Income [Abstract]
Net income	$ 7,675	$ 62,460	$ 9,255	$ 190,907
Other comprehensive income (loss):
Foreign currency translation adjustments	1,084	0	1,128	0
Change in unrealized gains on available-for-sale securities	1,565	(213)	1,908	172
Other comprehensive income (loss) before tax	2,649	(213)	3,036	172
Income tax expense related to items of other comprehensive income	(604)	(83)	(736)	(334)
Other comprehensive income (loss), net of tax	2,045	(296)	2,300	(162)
Comprehensive income	$ 9,720	$ 62,164	$ 11,555	$ 190,745