Reverse Mortgage Interests, Net - Unsecuritized Interest (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Reverse Mortgage Interest [Abstract]
Repurchased HECM loans (exceeds 98% MCA)	$ 941	$ 949
HECM related receivables	270	300
Funded borrower draws not yet securitized	114	76
REO-related receivables	24	16
Purchase discount	(95)	(122)
Total unsecuritized interests	$ 1,254	$ 1,219

Reverse Mortgage Interest [Abstract]

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Reverse Mortgage Interest, Unpaid Principal Balance, Unsecuritized

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Reverse Mortgage Interest, Unpaid Principal Balance, Unsecuritized, Funded Draws Not Yet Securitized

No definition available.

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Reverse Mortgage Interest, Unpaid Principal Balance, Unsecuritized, Home Equity Conversion Mortgage Receivables

No definition available.

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Reverse Mortgage Interest, Unpaid Principal Balance, Unsecuritized, Purchase Discount

No definition available.

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Reverse Mortgage Interest, Unpaid Principal Balance, Unsecuritized, Real Estate Owned Related Receivables

No definition available.

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Reverse Mortgage Interest, Unpaid Principal Balance, Unsecuritized, Repurchase of Home Equity Conversion Mortgages

No definition available.

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