Debt Debt (SOFTER Bank Loans Narrative) (Details) - USD ($) $ in Millions	1 Months Ended
	Jan. 31, 2017	Dec. 31, 2017
Debt Instrument [Line Items]
Debt, Long-term and Short-term, Combined Amount		$ 3,661
Bank Loans Acquired from SOFTER [Member]
Debt Instrument [Line Items]
Repayments of Debt	$ 69
Debt, Long-term and Short-term, Combined Amount		$ 70