Accumulated Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 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			8,523
Amounts reclassified from accumulated other comprehensive income			(3,648)
Other comprehensive income (loss)	(5,295)	6,052	4,875	4,142
Total accumulated other comprehensive income, ending balance	55,365		55,365
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			(835)
Amounts reclassified from accumulated other comprehensive income			0
Other comprehensive income (loss)			(835)
Total accumulated other comprehensive income, ending balance	566		566
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			9,358
Amounts reclassified from accumulated other comprehensive income			(3,648)
Other comprehensive income (loss)			5,710
Total accumulated other comprehensive income, ending balance	$ 54,799		$ 54,799