Securitizations and Financings - Assets and Liabilities of Consolidated VIEs (Details) $ in Millions	6 Months Ended
	Jun. 30, 2019 USD ($) special_purpose_entity	Dec. 31, 2018 USD ($)
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Number of SPEs | special_purpose_entity	4
Assets	$ 755	$ 816
Reverse Secured Borrowings, Assets, Carrying Amount	6,024	6,791
Liabilities	501	535
Reverse Secured Borrowings, Liabilities, Carrying Amount	5,937	6,699
Residential Mortgage | Restricted cash
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Assets	59	70
Reverse Secured Borrowings, Assets, Carrying Amount	40	63
Residential Mortgage | Reverse mortgage interests
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Assets	0	0
Reverse Secured Borrowings, Assets, Carrying Amount	5,975	6,728
Residential Mortgage | Advances and other receivables, net
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Assets	583	628
Reverse Secured Borrowings, Assets, Carrying Amount	0	0
Residential Mortgage | Mortgage loans held for investment, net
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Assets	113	118
Reverse Secured Borrowings, Assets, Carrying Amount	0	0
Residential Mortgage | Other assets
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Assets	0	0
Reverse Secured Borrowings, Assets, Carrying Amount	9	0
Residential Mortgage | Advance facilities
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities	478	505
Reverse Secured Borrowings, Liabilities, Carrying Amount	0	0
Residential Mortgage | Payables and other liabilities
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities	1	1
Reverse Secured Borrowings, Liabilities, Carrying Amount	0	1
Residential Mortgage | Participating interest financing
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities	0	0
Reverse Secured Borrowings, Liabilities, Carrying Amount	4,861	5,607
Residential Mortgage | Trust 2017-2 | Other non-recourse debt
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities	0	0
Reverse Secured Borrowings, Liabilities, Carrying Amount	0	231
Residential Mortgage | Trust 2018-1 | Other non-recourse debt
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities	0	0
Reverse Secured Borrowings, Liabilities, Carrying Amount	224	284
Residential Mortgage | Trust 2018-2 | Other non-recourse debt
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities	0	0
Reverse Secured Borrowings, Liabilities, Carrying Amount	182	250
Residential Mortgage | Trust 2018-3 | Other non-recourse debt
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities	0	0
Reverse Secured Borrowings, Liabilities, Carrying Amount	272	326
Residential Mortgage | Trust 2019-1 | Other non-recourse debt
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities	0	0
Reverse Secured Borrowings, Liabilities, Carrying Amount	398	0
Residential Mortgage | Other nonrecourse debt
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities	22	29
Reverse Secured Borrowings, Liabilities, Carrying Amount	$ 0	$ 0