Activities with Stockholders (Business Concentrations) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Related Party Transaction [Line Items]
Advances	$ 79,757		$ 80,360
Loans and Leases Receivable, Net Amount	9,546		9,334
Interest Income on Advances	399	$ 715
Wells Fargo Bank N.A. [Member]
Related Party Transaction [Line Items]
Capital Stock	$ 709		$ 1,029
Capital Stock Percentage	15.00%		22.00%
Advances	$ 17,450		$ 25,450
Loans and Leases Receivable, Net Amount	20		21
Interest Income on Advances	113	1,059
Superior Guaranty Insurance Company [Member]
Related Party Transaction [Line Items]
Capital Stock	$ 14		$ 15
Capital Stock Percentage	0.00%		0.00%
Advances	$ 0		$ 0
Loans and Leases Receivable, Net Amount	334		350
Interest Income on Advances	0	0
Principal Owner [Member]
Related Party Transaction [Line Items]
Capital Stock	$ 723		$ 1,044
Capital Stock Percentage	15.00%		22.00%
Advances	$ 17,450		$ 25,450
Loans and Leases Receivable, Net Amount	354		$ 371
Interest Income on Advances	$ 113	$ 1,059
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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- Definition

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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