Loans Mortgages With Potential Concentration of Credit Risk (Details) - USD ($) $ in Millions		Dec. 31, 2018		Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross	[1]	$ 151,839		$ 143,181
Fair Value, Concentration of Risk, Loans Receivable		$ 11,414		$ 10,843
Current Weighted Average FICO Score on Mortgages With Potential Concentration of Credit Risk		759		756
Residential Mortgage Interest Only Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair Value, Concentration of Risk, Loans Receivable	[2]	$ 492		$ 646
Residential Mortgage Amortizing Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair Value, Concentration of Risk, Loans Receivable	[3]	10,922		10,197
Interest Only Mortgage with MI or with Combined Original LTV less than 80% [Member] | Residential Mortgage Interest Only Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair Value, Concentration of Risk, Loans Receivable	[2]	464		569
Interest Only Mortgage with no MI and with Combined Original LTV greater than 80% [Member] | Residential Mortgage Interest Only Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Fair Value, Concentration of Risk, Loans Receivable	[2]	28		77
Geographic Distribution, Foreign [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		1,800		1,400
Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		$ 38,900		$ 38,600
Percentage of Loans Held for Investment		26.00%		27.00%
Federal National Mortgage Association (FNMA) Insured Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Gross		$ 459		$ 560
Government Guarantee Percent		1.00%	[4]	1.00%
Mortgage Loans on Real Estate [Member] | Credit Concentration Risk [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unused Commitments to Extend Credit		$ 2,700		$ 3,000

[1] Includes loans of consolidated VIEs of $153 million and $179 million at December?31, 2018 and December?31, 2017, respectively.

[2] Comprised of first and/or second liens, primarily with an initial 10 year interest only period.

[3] Comprised of loans with no MI.

[4] Includes 3,321 loans with a carrying value of $41 million that were modified prior to 2016 and reclassified as TDRs in the fourth quarter of 2016.