Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
AOCI Attributable to Parent, Net of Tax
Beginning balance	$ 934,389
Other comprehensive income before reclassifications	92	$ 932
Ending balance	924,088
AOCI Attributable to Parent [Member]
AOCI Attributable to Parent, Net of Tax
Beginning balance	(3,838)	(4,205)
Ending balance	$ (3,746)	$ (3,273)