Income Taxes (Schedule of Unrecognized Tax Benefits) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns
Balance at beginning of period	$ 3,747	$ 2,854	$ 1,526
Changes in tax positions of prior years	(174)	214	912
Additions based on tax positions related to the current year	1,255	1,252	866
Payments	(211)	0	(85)
Closure of tax years	(472)	(573)	(365)
Balance at end of period	$ 4,145	$ 3,747	$ 2,854