Income Taxes (Unrecognized Tax Benefits) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Unrecognized Tax Benefits [Roll Forward]
Balance as of January 1	$ 1,839	$ 616	$ 581
Unrecognized Tax Benefits, Increases Resulting from Prior Period Tax Positions		0	100
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions	(246)
Increases for positions taken in current periods	1,957	1,584	0
Decreases in unrecorded tax positions related to settlement with the taxing authorities	(607)	(361)	0
Decreases in unrecorded tax positions related to lapse of statute of limitations	0	0	(65)
Balance as of December 31	$ 2,943	$ 1,839	$ 616