Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2018
Operating Loss Carryforwards [Line Items]
Additions for tax positions related to current year	$ 29	$ 55	$ 88	$ 3,335
Effective income tax rate	5.42%		6.64%
Income tax expense	$ 1,679	$ (204)	$ 6,027	363
Income Tax Expense (Benefit), before discrete items	$ (1,650)		$ (5,939)
Effective Income Tax Rate Reconciliation, Excluding Discrete Items, Percent	5.30%		6.50%
Unrecognized Tax Benefits	$ 9,232		$ 9,232
Unrecognized tax benefits, period increase (decrease)			$ (88)	$ (3,335)
United States
Operating Loss Carryforwards [Line Items]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent			21.00%
Scenario, Forecast
Operating Loss Carryforwards [Line Items]
Effective income tax rate					6.54%