Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
Beginning balance	$ 394,498
Other comprehensive income (loss)	(7,631)	$ 357
Ending balance	398,225
AOCI Attributable to Parent [Member]
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
Beginning balance	37,858
Other comprehensive income before reclassifications	(356)
Amounts reclassified from accumulated other comprehensive income	(7,275)
Other comprehensive income (loss)	(7,631)
Ending balance	30,227
Foreign Currency [Member]
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
Beginning balance	(1,066)
Other comprehensive income before reclassifications	419
Amounts reclassified from accumulated other comprehensive income	0
Other comprehensive income (loss)	419
Ending balance	(647)
Unrealized Holding Gains on Available-for-sale Securities [Member]
Changes in Accumulated Other Comprehensive Income by Component [Roll Forward]
Beginning balance	38,924
Other comprehensive income before reclassifications	(775)
Amounts reclassified from accumulated other comprehensive income	(7,275)
Other comprehensive income (loss)	(8,050)
Ending balance	$ 30,874