Segment Information (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) segment	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Segment Reporting Information [Line Items]
Number of Reportable Segments | segment	8
Total deferred gain (loss)	$ 222
Synthetic Gic Fees	147	$ 146	$ 159
Segment Reconciling Items
Segment Reporting Information [Line Items]
Derivative, Gain (Loss) on Derivative, Net, Terminated Or Offset Before Maturity	$ 41	$ 19	$ 53