Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2017
Operating Loss Carryforwards [Line Items]
Income tax expense	$ 869	$ 1,750
Effective income tax rate	3.20%		1.26%
Income Tax Expense (Benefit), before discrete items	$ (351)
Effective Income Tax Rate Reconciliation, Excluding Discrete Items, Percent	1.30%
Unrecognized Tax Benefits	$ 3,783
Unrecognized tax benefits, period increase (decrease)	$ 518	$ 50
United States
Operating Loss Carryforwards [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	35.00%