Accumulated Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
Total accumulated other comprehensive income, beginning balance			$ 50,490
Other comprehensive income before reclassifications			12,699
Amounts reclassified from accumulated other comprehensive income			(2,529)
Other comprehensive income (loss)	5,488	(2,614)	10,170	(1,910)
Total accumulated other comprehensive income, ending balance	60,660		60,660
Foreign Currency [Member]
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
Total accumulated other comprehensive income, beginning balance			1,401
Other comprehensive income before reclassifications			(130)
Amounts reclassified from accumulated other comprehensive income			0
Other comprehensive income (loss)			(130)
Total accumulated other comprehensive income, ending balance	1,271		1,271
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			49,089
Other comprehensive income before reclassifications			12,829
Amounts reclassified from accumulated other comprehensive income			(2,529)
Other comprehensive income (loss)			10,300
Total accumulated other comprehensive income, ending balance	$ 59,389		$ 59,389