Income Taxes (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Income Taxes [Abstract]
Discrete charge for an uncertain tax position	$ 0	$ 520	$ 20	$ 953
Discrete charge associated with disproportionate tax effect	$ 109		344
Payments on tax audit liability			$ 939
Foreign statutory tax rate, foreign operations	25.00%		25.00%
Gross deferred tax asset					$ 75,416
Valuation allowance					67,662
Net deferred tax asset					7,754
Deferred tax liabilities, gross					16,720
Foreign Earnings Repatriated	$ 10,800
Discrete expense related to alternative minimum tax	211
Discrete expense related to tax amortization of indefinite lived intangibles and goodwill	101
Increase to the deferred tax liabilities	$ 101
Net operating loss carryforwards for U.S. federal income tax purposes					172,419
Tax windfall					270
Research and experimentation credit carryforwards					3,407
Alternative minimum tax credit carryforwards					$ 315
AMT percentage					20.00%
Maximum percentage of income offset by available NOLs					90.00%
Net operating loss carryforwards, net of limitations					$ 172,149