Taxes (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2020	Dec. 31, 2016
Operating Loss Carryforwards [Line Items]
Valuation allowance	$ 506,316	$ 506,316	$ 530,612	$ 610,600
Annual limitation on operating loss use	29,800	29,800
Income tax benefit from cumulative adjustments		48,800
Change in uncertain tax positions		26,600
Operating loss carryforwards	1,000,000	1,000,000
Tax Cuts and Jobs Act of 2017, Income tax expense (benefit)			16,700	(330,900)
Repatriation of foreign earnings		1,500
Cumulative foreign earnings		4,200
Tax Cuts and Jobs Act of 2017, Income tax expense (benefit) related to valuation allowance	(45,000)
Tax Cuts and Jobs Act of 2017, Provisional income tax expense (benefit) related to change in limit on deductible for covered employees		3,900	6,100	200
Decrease in valuation allowance		24,200		35,700
Interest and penalties accrued related to unrecognized tax benefits	800	800	300
Gross unrecognized tax benefits	$ 39,729	$ 39,729	$ 39,093	$ 11,383		$ 7,455
Scenario, forecast
Operating Loss Carryforwards [Line Items]
Gross unrecognized tax benefits					$ 500