Income Taxes (Gross Unrecognized Tax Benefits) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Balance at beginning of period	$ 915	$ 3,671	$ 3,285
Additions based on tax positions related to prior years	0	181
Reductions based on tax positions related to prior years			(256)
Additions based on tax positions related to the current year	82	211	642
Reductions due to settlements with taxing authorities	0	(1,330)	0
Reductions due to lapse of the applicable statute of limitations	0	(1,818)	0
Balance at end of period	$ 997	$ 915	$ 3,671