Accumulated Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 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			13,417
Amounts reclassified from accumulated other comprehensive income			(9,275)
Other comprehensive income	6,053	4,849	4,142	8,230
Total accumulated other comprehensive income, ending balance	41,585		41,585
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			(282)
Amounts reclassified from accumulated other comprehensive income			0
Other comprehensive income			(282)
Total accumulated other comprehensive income, ending balance	1,694		1,694
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			13,699
Amounts reclassified from accumulated other comprehensive income			(9,275)
Other comprehensive income			4,424
Total accumulated other comprehensive income, ending balance	$ 39,891		$ 39,891