Taxes (Narrative) (Details) - USD ($)	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Oct. 02, 2016	Oct. 01, 2016
Operating Loss Carryforwards [Line Items]
Cancellation of debt income				$ 3,353,000,000
Decrease in operating loss carryforwards					$ 3,015,000,000
Decrease in tax basis of assets					3,200,000
Operating loss carryforwards	$ 931,100,000	$ 931,100,000
Annual limitation on operating loss use	29,800,000.0	29,800,000.0
Increase (decrease) in valuation allowance	(1,289,000,000)		$ 865,100,000
Additional valuation allowance	1,185,000,000	1,185,000,000
Net operating loss carryforwards	1,022,000,000	1,022,000,000	1,135,000,000
Interest and penalties accrued related to unrecognized tax benefits	$ 500,000	500,000	$ 1,700,000
Reductions as a result of lapses in the statute of limitations		$ 37,110,000
Alternative Minimum Tax Credits [Member]
Operating Loss Carryforwards [Line Items]
Decrease in tax credit carryforwards					92,000,000
Tax credit carryforwards				22,800,000
Capital Loss Carryforward [Member]
Operating Loss Carryforwards [Line Items]
Decrease in tax credit carryforwards					$ 59,200,000
Tax credit carryforwards				5,900,000
Domestic Tax Authority [Member]
Operating Loss Carryforwards [Line Items]
Operating loss carryforwards				$ 931,100,000