Debt (Long-term Debt) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2021
Debt Instrument [Line Items]
Total long-term debt	$ 22,006	$ 17,029
Subordinated debt	1,000	1,000
Secured debt	9,992	7,619
Loss on extinguishment of FHLB debt	99
Long-term debt, due within one year	5,085	5,869
Long-term debt, due after one year	16,921	11,160
Debt converted from fixed-rate into variable-rate	2,500
Unsecured debt
Debt Instrument [Line Items]
Fixed rate	9,251	9,297
Trust preferred securities	2,578
Hedge basis adjustments	185	113
Total long-term debt	$ 12,014	$ 9,410
Weighted average stated interest rate	5.23%	4.87%
Long-term debt, due within one year	$ 647	$ 1,028
Long-term debt, due after one year	$ 11,367	$ 8,382
Unsecured debt \| Minimum
Debt Instrument [Line Items]
Interest rate	8.00%	0.60%
Unsecured debt \| Maximum
Debt Instrument [Line Items]
Interest rate	0.70%	8.00%
Secured debt
Debt Instrument [Line Items]
Fixed rate	$ 9,909	$ 7,502
Hedge basis adjustments	(16)	(3)
Total long-term debt	9,992	7,619
Variable rate	$ 99	$ 120
Weighted average stated interest rate	2.51%	2.14%
Variable interest entity debt	$ 4,200	$ 1,300
Long-term debt, due within one year	4,438	4,841
Long-term debt, due after one year	$ 5,554	$ 2,778
Secured debt \| Minimum
Debt Instrument [Line Items]
Interest rate	1.45%	0.72%
Secured debt \| Maximum
Debt Instrument [Line Items]
Interest rate	3.70%	6.86%
Federal Home Loan Bank advances
Debt Instrument [Line Items]
Secured debt	$ 5,800	$ 6,300

Debt converted from fixed-rate into variable-rate

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- Definition

Long-term Debt, Fair Value Hedge Basis Adjustment

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- Definition

Loss on Extinguishment of FHLB Debt

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- Definition

Trust preferred securities

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- Definition

Variable Interest Entity Debt

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Weighted average interest rate of debt outstanding.

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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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The portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a set, unchanging rate.

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The portion of the carrying amount of long-term borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a rate subject to change from time to time.

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- Definition

Carrying value as of the balance sheet date, including the current and noncurrent portions, of collateralized debt obligations (with maturities initially due after one year or beyond the operating cycle, if longer). Such obligations include mortgage loans, chattel loans, and any other borrowings secured by assets of the borrower.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of subordinated debt (with initial maturities beyond one year or beyond the operating cycle if longer). Subordinated debt places a lender in a lien position behind debt having a higher priority of repayment in liquidation of the entity's assets.

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