Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2017
Operating Loss Carryforwards [Line Items]
Income tax expense	$ (302)	$ (1,418)	$ 567	$ 332
Effective income tax rate	(1.28%)		1.11%		1.63%
Income Tax Expense (Benefit), before discrete items	$ (439)		$ 790
Effective Income Tax Rate Reconciliation, Excluding Discrete Items, Percent	1.90%		1.60%
Unrecognized Tax Benefits	$ 6,545		$ 6,545
Unrecognized tax benefits, period increase (decrease)			$ 3,280	$ 50
United States
Operating Loss Carryforwards [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent			35.00%