Securitizations and Financings - Assets and Liabilities of Consolidated VIEs (Details) $ in Millions	9 Months Ended
	Sep. 30, 2018 USD ($) special_purpose_entity	Dec. 31, 2017 USD ($)
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Number of SPEs | special_purpose_entity	4
Assets	$ 914
Reverse Secured Borrowings, Assets, Carrying Amount	7,192
Liabilities	596
Reverse Secured Borrowings, Liabilities, Carrying Amount	7,052
Residential Mortgage | Restricted cash
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Assets	111
Reverse Secured Borrowings, Assets, Carrying Amount	52
Residential Mortgage | Reverse mortgage interests, net
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Assets	0
Reverse Secured Borrowings, Assets, Carrying Amount	7,140
Residential Mortgage | Advances and other receivables, net
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Assets	682
Reverse Secured Borrowings, Assets, Carrying Amount	0
Residential Mortgage | Mortgage loans held for investment, net
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Assets	121
Reverse Secured Borrowings, Assets, Carrying Amount	0
Residential Mortgage | Other assets
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Assets	0
Reverse Secured Borrowings, Assets, Carrying Amount	0
Residential Mortgage | Advance facilities
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities	563
Reverse Secured Borrowings, Liabilities, Carrying Amount	0
Residential Mortgage | Payables and accrued liabilities
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities	1
Reverse Secured Borrowings, Liabilities, Carrying Amount	1
Residential Mortgage | Participating interest financing
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities	0
Reverse Secured Borrowings, Liabilities, Carrying Amount	6,021
Residential Mortgage | Trust 2016-2 | Other non-recourse debt
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities	0
Reverse Secured Borrowings, Liabilities, Carrying Amount	0
Residential Mortgage | Trust 2016-3 | Other non-recourse debt
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities	0
Reverse Secured Borrowings, Liabilities, Carrying Amount	0
Residential Mortgage | Trust 2017-1 | Other non-recourse debt
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities	0
Reverse Secured Borrowings, Liabilities, Carrying Amount	151
Residential Mortgage | Trust 2017-2 | Other non-recourse debt
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities	0
Reverse Secured Borrowings, Liabilities, Carrying Amount	258
Residential Mortgage | Trust 2018-1 | Other non-recourse debt
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities	0
Reverse Secured Borrowings, Liabilities, Carrying Amount	329
Residential Mortgage | Trust 2018-2 | Other non-recourse debt
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities	0
Reverse Secured Borrowings, Liabilities, Carrying Amount	292
Residential Mortgage | Other nonrecourse debt
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities	32
Reverse Secured Borrowings, Liabilities, Carrying Amount	$ 0
Predecessor
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Assets		$ 1,142
Reverse Secured Borrowings, Assets, Carrying Amount		8,007
Liabilities		793
Reverse Secured Borrowings, Liabilities, Carrying Amount		7,922
Predecessor | Residential Mortgage | Restricted cash
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Assets		106
Reverse Secured Borrowings, Assets, Carrying Amount		26
Predecessor | Residential Mortgage | Reverse mortgage interests, net
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Assets		0
Reverse Secured Borrowings, Assets, Carrying Amount		7,981
Predecessor | Residential Mortgage | Advances and other receivables, net
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Assets		896
Reverse Secured Borrowings, Assets, Carrying Amount		0
Predecessor | Residential Mortgage | Mortgage loans held for investment, net
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Assets		138
Reverse Secured Borrowings, Assets, Carrying Amount		0
Predecessor | Residential Mortgage | Other assets
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Assets		2
Reverse Secured Borrowings, Assets, Carrying Amount		0
Predecessor | Residential Mortgage | Advance facilities
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities		749
Reverse Secured Borrowings, Liabilities, Carrying Amount		0
Predecessor | Residential Mortgage | Payables and accrued liabilities
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities		2
Reverse Secured Borrowings, Liabilities, Carrying Amount		1
Predecessor | Residential Mortgage | Participating interest financing
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities		0
Reverse Secured Borrowings, Liabilities, Carrying Amount		7,111
Predecessor | Residential Mortgage | Trust 2016-2 | Other non-recourse debt
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities		0
Reverse Secured Borrowings, Liabilities, Carrying Amount		94
Predecessor | Residential Mortgage | Trust 2016-3 | Other non-recourse debt
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities		0
Reverse Secured Borrowings, Liabilities, Carrying Amount		138
Predecessor | Residential Mortgage | Trust 2017-1 | Other non-recourse debt
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities		0
Reverse Secured Borrowings, Liabilities, Carrying Amount		213
Predecessor | Residential Mortgage | Trust 2017-2 | Other non-recourse debt
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities		0
Reverse Secured Borrowings, Liabilities, Carrying Amount		365
Predecessor | Residential Mortgage | Trust 2018-1 | Other non-recourse debt
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities		0
Reverse Secured Borrowings, Liabilities, Carrying Amount		0
Predecessor | Residential Mortgage | Trust 2018-2 | Other non-recourse debt
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities		0
Reverse Secured Borrowings, Liabilities, Carrying Amount		0
Predecessor | Residential Mortgage | Other nonrecourse debt
Assets and Associated Liabilities of Transfers Accounted for as Secured Borrowings [Line Items]
Liabilities		42
Reverse Secured Borrowings, Liabilities, Carrying Amount		$ 0