Income Taxes (Deferred Tax Liabilities and Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Non-current deferred tax assets	$ 43,870	$ 31,686
ASU 2013-11 reclass, described below	(341)	(341)	$ (341)
Long-term deferred income tax assets	$ 43,529	$ 31,345