Income Taxes (Summary of Deferred Income Tax Asset Valuation Allowance) (Details) - Deferred income tax asset valuation allowance - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	$ 80,796	$ 109,913	$ 107,312
Additions (reductions) charged to expense	14,602	(28,071)	20,450
Other	0	(1,046)	(17,849)
Balance at end of year	$ 95,398	$ 80,796	$ 109,913