Mortgage Loans Aging (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Financing Receivable, Past Due [Line Items]
Days delinquent	$ 198,914		$ 55,266
Current	3,268,165		3,281,663
Total recorded investment in loans	3,467,079		3,336,929
Recorded investment in loans 90 days or more delinquent and accruing interest	72,906		164
Recorded investment in nonaccrual loans	28,069	$ 27,265	27,981
Table Footnote [Abstract]
Financing Receivable, Nonaccrual, No Allowance	9,246
Financing Receivable, before Allowance for Credit Loss	3,464,721		3,336,405
30 to 59 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Days delinquent	45,680		31,240
60 to 89 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Days delinquent	57,421		8,326
Seriously Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Days delinquent	95,813		15,700
Single-family [Member]
Financing Receivable, Past Due [Line Items]
Days delinquent	194,140		55,144
Current	2,922,295		2,951,167
Total recorded investment in loans	3,116,435		3,006,311
Recorded investment in loans 90 days or more delinquent and accruing interest	71,459		164
Recorded investment in nonaccrual loans	27,753	27,174	27,546
Table Footnote [Abstract]
Financing Receivable, Nonaccrual, No Allowance	9,211
Financing Receivable, before Allowance for Credit Loss	$ 3,100,807
Single-family [Member] | Minimum [Member]
Table Footnote [Abstract]
Serious delinquency, days past due	90 days
Single-family [Member] | 30 to 59 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Days delinquent	$ 44,520		31,233
Single-family [Member] | 60 to 89 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Days delinquent	57,421		8,326
Single-family [Member] | Seriously Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Days delinquent	92,199		15,585
Single-family [Member] | FixedRateResidentialMortgage15yearMember
Financing Receivable, Past Due [Line Items]
Days delinquent	11,996		2,347
Current	389,389		371,740
Total recorded investment in loans	401,385		374,087
Recorded investment in loans 90 days or more delinquent and accruing interest	4,175		0
Recorded investment in nonaccrual loans	844	856	858
Table Footnote [Abstract]
Financing Receivable, Nonaccrual, No Allowance	554
Financing Receivable, before Allowance for Credit Loss	401,385
Single-family [Member] | FixedRateResidentialMortgage15yearMember | 30 to 59 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Days delinquent	3,048		1,616
Single-family [Member] | FixedRateResidentialMortgage15yearMember | 60 to 89 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Days delinquent	4,164		286
Single-family [Member] | FixedRateResidentialMortgage15yearMember | Seriously Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Days delinquent	4,784		445
Single-family [Member] | Other [Member]
Financing Receivable, Past Due [Line Items]
Days delinquent	8,606		5,043
Current	54,920		64,726
Total recorded investment in loans	63,526		69,769
Recorded investment in loans 90 days or more delinquent and accruing interest	2,813		136
Recorded investment in nonaccrual loans	2,851	2,827	2,973
Table Footnote [Abstract]
Financing Receivable, Nonaccrual, No Allowance	799
Financing Receivable, before Allowance for Credit Loss	47,898
Single-family [Member] | Other [Member] | 30 to 59 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Days delinquent	1,870		2,323
Single-family [Member] | Other [Member] | 60 to 89 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Days delinquent	1,727		829
Single-family [Member] | Other [Member] | Seriously Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Days delinquent	5,009		1,891
Single-family [Member] | Adjustable Rate Residential Mortgage [Member]
Financing Receivable, Past Due [Line Items]
Days delinquent	2,436		664
Current	37,138		44,244
Total recorded investment in loans	39,574		44,908
Recorded investment in loans 90 days or more delinquent and accruing interest	879		0
Table Footnote [Abstract]
Financing Receivable, Nonaccrual, No Allowance	149
Financing Receivable, before Allowance for Credit Loss	39,574
Single-family [Member] | Adjustable Rate Residential Mortgage [Member] | 30 to 59 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Days delinquent	523		412
Single-family [Member] | Adjustable Rate Residential Mortgage [Member] | 60 to 89 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Days delinquent	829		85
Single-family [Member] | Adjustable Rate Residential Mortgage [Member] | Seriously Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Days delinquent	1,084		167
Single-family [Member] | Fixed Rate Residential Mortgage
Financing Receivable, Past Due [Line Items]
Days delinquent	171,102		47,090
Current	2,440,848		2,470,457
Total recorded investment in loans	2,611,950		2,517,547
Recorded investment in loans 90 days or more delinquent and accruing interest	63,592		28
Recorded investment in nonaccrual loans	23,783	23,212	23,427
Table Footnote [Abstract]
Financing Receivable, Nonaccrual, No Allowance	7,709
Financing Receivable, before Allowance for Credit Loss	2,611,950
Single-family [Member] | Fixed Rate Residential Mortgage | 30 to 59 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Days delinquent	39,079		26,882
Single-family [Member] | Fixed Rate Residential Mortgage | 60 to 89 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Days delinquent	50,701		7,126
Single-family [Member] | Fixed Rate Residential Mortgage | Seriously Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Days delinquent	81,322		13,082
Multifamily [Member]
Financing Receivable, Past Due [Line Items]
Days delinquent	4,774		122
Current	345,870		330,496
Total recorded investment in loans	350,644		330,618
Recorded investment in loans 90 days or more delinquent and accruing interest	1,447		0
Recorded investment in nonaccrual loans	316	$ 91	435
Table Footnote [Abstract]
Financing Receivable, Nonaccrual, No Allowance	$ 35
Multifamily [Member] | Minimum [Member]
Table Footnote [Abstract]
Serious delinquency, days past due	60 days
Multifamily [Member] | Maximum [Member]
Table Footnote [Abstract]
Serious delinquency, days past due	89 days
Multifamily [Member] | 30 to 59 Days Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Days delinquent	$ 1,160		7
Multifamily [Member] | Seriously Delinquent [Member]
Financing Receivable, Past Due [Line Items]
Days delinquent	$ 3,614		$ 115