Activities with Stockholders (Business Concentrations) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Related Party Transaction [Line Items]
Advances	$ 80,360	$ 106,323
Loans and Leases Receivable, Net Amount	9,334	7,835
Interest Income on Advances	2,466	2,443	$ 1,589
Wells Fargo Bank N.A. [Member]
Related Party Transaction [Line Items]
Capital Stock	$ 1,029	$ 1,994
Capital Stock Percentage	22.00%	35.00%
Advances	$ 25,450	$ 49,575
Loans and Leases Receivable, Net Amount	21	25
Interest Income on Advances	1,059	1,167
Superior Guaranty Insurance Company [Member]
Related Party Transaction [Line Items]
Capital Stock	$ 15	$ 18
Capital Stock Percentage	0.00%	0.00%
Advances	$ 0	$ 0
Loans and Leases Receivable, Net Amount	350	420
Interest Income on Advances	0	0
Principal Owner [Member]
Related Party Transaction [Line Items]
Capital Stock	$ 1,044	$ 2,012
Capital Stock Percentage	22.00%	35.00%
Advances	$ 25,450	$ 49,575
Loans and Leases Receivable, Net Amount	371	445
Interest Income on Advances	$ 1,059	$ 1,167
Stockholders' Equity, Total [Member] \| Stockholders' Capital Stock Outstanding Concenetration Risk [Member] \| Minimum [Member]
Related Party Transaction [Line Items]
Business Concentration Percentage	10.00%

Capital Stock Value Including Mandatorily Redeemable Stock

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Capital Stock Value Including Mandatorily Redeemable Stock Percent

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Amount of Federal Home Loan Bank (FHLBank) advances to member financial institutions.

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Amount of interest income from Federal Home Loan Bank (FHLBank) advances to member financial institutions.

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

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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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