Variable Interest Entities Variable Interest Entities - Unpaid Principal (Details) - Variable Interest Entity, Primary Beneficiary [Member] - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Variable Interest Entity [Line Items]
FG VIEs’ assets	$ 279	$ 350
FG VIEs' liabilities with recourse	21	48
FG VIEs’ liabilities without recourse	19	28
Unpaid principal balance for FG VIEs’ assets that were 90 days or more past due	61	71
Unpaid principal for FG VIEs’ liabilities with recourse	$ 409	$ 565