Other Comprehensive Income (Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Other comprehensive income (loss), before-tax amount
Foreign currency translation adjustments, before-tax amount	$ 3,990	$ (892)	$ 5,278	$ (7,792)
Unrealized holding gains (losses) on available-for-sale securities, before tax amount	141,781	(132,065)	123,409	(38,996)
Recognition of previously unrealized (gains) losses on available-for-sale securities included in net income (loss), before tax amount	(68,899)	(56)	(152,921)	(1,694)
Other comprehensive income (loss), before-tax amount	76,872	(133,013)	(24,234)	(48,482)
Other comprehensive income (loss):
Foreign currency translation adjustments, net of tax	3,990	(892)	5,278	(7,792)
Unrealized holding gains (losses) on available-for-sale securities, net of tax	141,781	(132,065)	123,409	(38,996)
Recognition of previously unrealized (gains) losses on available-for-sale securities included in net income (loss)	(68,899)	(56)	(152,921)	(1,694)
Total other comprehensive income (loss), net of tax	76,872	(133,013)	(24,234)	(48,482)
Accumulated other comprehensive income (loss)
Foreign currency translation adjustments, balance at beginning of period, net			(9,139)
Foreign currency translation adjustments, before-tax amount, current period activity	3,990	(892)	5,278	(7,792)
Foreign currency translation adjustments, balance at end of period, net	(3,861)		(3,861)
Unrealized / Recognized Gains (Losses), balance at beginning of period, net			91,182
Unrealized / Recognized Gains (Losses), Current period activity			(29,512)
Unrealized / Recognized Gains (Losses), balance at end of period, net	61,670		61,670
Accumulated other comprehensive income (loss), balance at beginning of period, net			82,043
Other comprehensive income (loss), current period activity	76,872	(133,013)	(24,234)	(48,482)
Other comprehensive income (loss), tax (expense) benefit	0
Accumulated other comprehensive income (loss), balance at end of period, net	$ 57,809		$ 57,809