Accumulated Other Comprehensive Income (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
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
Total accumulated other comprehensive income, beginning balance			$ 37,443
Other comprehensive income before reclassifications			6,298
Amounts reclassified from accumulated other comprehensive income			(8,208)
Other comprehensive income (loss)	(2,614)	(4,488)	(1,910)	3,381
Total accumulated other comprehensive income, ending balance	35,533		35,533
Foreign Currency [Member]
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
Total accumulated other comprehensive income, beginning balance			1,976
Other comprehensive income before reclassifications			(481)
Amounts reclassified from accumulated other comprehensive income			0
Other comprehensive income (loss)			(481)
Total accumulated other comprehensive income, ending balance	1,495		1,495
Unrealized holding gains on available-for-sale securities [Member]
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
Total accumulated other comprehensive income, beginning balance			35,467
Other comprehensive income before reclassifications			6,779
Amounts reclassified from accumulated other comprehensive income			(8,208)
Other comprehensive income (loss)			(1,429)
Total accumulated other comprehensive income, ending balance	$ 34,038		$ 34,038