Other Comprehensive Income (Loss) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Other comprehensive income (loss), before-tax amount
Foreign currency translation adjustments, before-tax amount	$ 2,862	$ (1,965)	$ 5,599	$ 1,288
Unrealized holding gains (losses) on available-for-sale securities, before tax amount	19,285	(69,393)	37,068	(18,372)
Recognition of previously unrealized (gains) losses on available-for-sale securities included in net income (loss), before tax amount	(6,706)	(3,135)	(5,344)	(84,022)
Other comprehensive income (loss), before-tax amount	15,441	(74,493)	37,323	(101,106)
Other comprehensive income loss tax (expense) benefit
Unrealized holding gains (losses) on available-for-sale securities, tax (expense) benefit	(4,597)		(11,593)
Other Comprehensive Income (Loss), Tax	(4,597)		(11,593)
Other comprehensive income (loss):
Foreign currency translation adjustments, net of tax	2,862	(1,965)	5,599	1,288
Unrealized holding gains (losses) on available-for-sale securities, net of tax	14,688	(69,393)	25,475	(18,372)
Recognition of previously unrealized (gains) losses on available-for-sale securities included in net income (loss)	(6,706)	(3,135)	(5,344)	(84,022)
Total other comprehensive income (loss), net of tax	10,844	(74,493)	25,730	(101,106)
Accumulated other comprehensive income (loss)
Foreign currency translation adjustments, balance at beginning of period, net			(5,033)
Foreign currency translation adjustments, before-tax amount, other comprehensive income (loss) before reclassification	2,862	(1,965)	5,599	1,288
Foreign currency translation adjustments, balance at end of period, net	566		566
Unrealized / Recognized Gains (Losses), balance at beginning of period, net			193,836
Unrealized / Recognized Gains (Losses), before-tax amount, other comprehensive income (loss) before reclassification			37,068
Unrealized / Recognized Gains (Losses), before-tax amount, amounts reclassified from accumulated other comprehensive income (loss)	(6,706)	(3,135)	(5,344)	(84,022)
Unrealized holding gains (losses) on available-for-sale securities, tax (expense) benefit	(4,597)		(11,593)
Unrealized / Recognized Gains (Losses), balance at end of period, net	213,967		213,967
Accumulated other comprehensive income (loss), balance at beginning of period, net			188,803
Other comprehensive income (loss), before-tax amount, other comprehensive income (loss) before reclassification			42,667
Other comprehensive income (loss), before-tax amount, amounts reclassified from accumulated other comprehensive income (loss)			(5,344)
Other Comprehensive Income (Loss), tax (expense) benefit	(4,597)		(11,593)
Accumulated other comprehensive income (loss), balance at end of period, net	$ 214,533		$ 214,533