Income Taxes - Valuation and Qualifying Accounts (Details) - SEC Schedule, 12-09, Valuation Allowance, Deferred Tax Asset [Member] - 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 Period	$ 285,784	$ 249,560	$ 235,339
Other Adjustments	12,308	28,233	(12,419)
Additions Charged to Costs and Expenses	25,730	7,991	26,640
Balance at End of Period, Noncurrent	$ 323,822	$ 285,784	$ 249,560