Mortgage Loans Held for Sale and Investment - Reconciliation to Cash Flow (Details) - USD ($) $ in Millions	2 Months Ended	7 Months Ended	9 Months Ended
	Sep. 30, 2018	Jul. 31, 2018	Sep. 30, 2017
Loans Receivable Held-for-sale, Net, Reconciliation to Cash Flow [Roll Forward]
Balance - beginning of period	$ 1,514
Mortgage loans originated and purchased, net of fees	3,459
Loans sold	(3,508)
Repurchase of loans out of Ginnie Mae securitizations	223
Transfer of mortgage loans held for sale to advances/accounts receivable, net related to claims	(2)
Net transfer of mortgage loans held for sale from REO in other assets	4
Changes in fair value	(8)
Other purchase-related activities	(1)
Balance - end of period	1,681	$ 1,514
Predecessor
Loans Receivable Held-for-sale, Net, Reconciliation to Cash Flow [Roll Forward]
Balance - beginning of period	$ 1,514	1,891	$ 1,788
Mortgage loans originated and purchased, net of fees		12,319	13,988
Loans sold		(13,255)	(15,107)
Repurchase of loans out of Ginnie Mae securitizations		544	943
Transfer of mortgage loans held for sale to advances/accounts receivable, net related to claims		(7)	(16)
Net transfer of mortgage loans held for sale from REO in other assets		14	20
Changes in fair value		(1)	16
Other purchase-related activities		9	14
Balance - end of period		$ 1,514	$ 1,646