Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			$ 394,498
Other comprehensive income before reclassifications			3,115
Amounts reclassified from accumulated other comprehensive income			(6,822)
Other comprehensive income (loss)	$ 3,924	$ (56)	(3,707)	$ 301
Ending balance	404,313		404,313
AOCI Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			37,858
Ending balance	34,151		34,151
Foreign Currency [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			(1,066)
Other comprehensive income before reclassifications			543
Amounts reclassified from accumulated other comprehensive income			0
Other comprehensive income (loss)			543
Ending balance	(523)		(523)
Unrealized Holding Gains on Available-for-sale Securities [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			38,924
Other comprehensive income before reclassifications			2,572
Amounts reclassified from accumulated other comprehensive income			(6,822)
Other comprehensive income (loss)			(4,250)
Ending balance	$ 34,674		$ 34,674