Fair Value - Valuation Inputs (Details)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale	$ 696,000,000	$ 837,000,000
Net derivatives	172,000,000	171,000,000
Mortgage loans	3,645,000,000	4,964,000,000
Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	50,129,000,000	88,206,000,000
Available-for-sale	696,000,000	837,000,000
Total nonrecurring assets at fair value	54,645,000,000	94,428,000,000
Mortgage loans	3,645,000,000	4,964,000,000
Significant Unobservable Inputs (Level 3)
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	47,000,000	57,000,000
Available-for-sale	634,000,000	753,000,000
Mortgage loans held for sale, at lower of cost or fair value	2,029,000,000	5,307,000,000
Total nonrecurring assets at fair value	174,762,000,000	215,567,000,000
Mortgage loans	171,857,000,000	209,090,000,000
Significant Unobservable Inputs (Level 3) | Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	47,000,000	57,000,000
Available-for-sale	634,000,000	753,000,000
Net derivatives	(37,000,000)	131,000,000
Total nonrecurring assets at fair value	1,253,000,000	1,717,000,000
Mortgage loans	543,000,000	755,000,000
Significant Unobservable Inputs (Level 3) | Recurring | Discounted Cash Flow
Fair Value Inputs, Quantitative Information [Line Items]
Net derivatives	(62,000,000)	(21,000,000)
Significant Unobservable Inputs (Level 3) | Recurring | Dealer Mark
Fair Value Inputs, Quantitative Information [Line Items]
Net derivatives	25,000,000	152,000,000
Significant Unobservable Inputs (Level 3) | Nonrecurring
Fair Value Inputs, Quantitative Information [Line Items]
Mortgage loans held for sale, at lower of cost or fair value	1,663,000,000	1,584,000,000
Total nonrecurring assets at fair value	4,462,000,000	2,872,000,000
Other liabilities, fair value	0	0
Significant Unobservable Inputs (Level 3) | Nonrecurring | Single-Family
Fair Value Inputs, Quantitative Information [Line Items]
Acquired property, net	400,000,000	209,000,000
Significant Unobservable Inputs (Level 3) | Nonrecurring | Multifamily
Fair Value Inputs, Quantitative Information [Line Items]
Mortgage loans	644,000,000	178,000,000
Significant Unobservable Inputs (Level 3) | Nonrecurring | Various | Single-Family
Fair Value Inputs, Quantitative Information [Line Items]
Acquired property, net	12,000,000	11,000,000
Significant Unobservable Inputs (Level 3) | Nonrecurring | Various | Multifamily
Fair Value Inputs, Quantitative Information [Line Items]
Acquired property, net	119,000,000	34,000,000
Significant Unobservable Inputs (Level 3) | Nonrecurring | Consensus
Fair Value Inputs, Quantitative Information [Line Items]
Mortgage loans held for sale, at lower of cost or fair value	1,571,000,000	201,000,000
Significant Unobservable Inputs (Level 3) | Nonrecurring | Single Vendor
Fair Value Inputs, Quantitative Information [Line Items]
Mortgage loans held for sale, at lower of cost or fair value	92,000,000	1,383,000,000
Significant Unobservable Inputs (Level 3) | Nonrecurring | Internal Model | Single-Family
Fair Value Inputs, Quantitative Information [Line Items]
Mortgage loans	1,636,000,000	867,000,000
Acquired property, net	215,000,000	75,000,000
Significant Unobservable Inputs (Level 3) | Nonrecurring | Internal Model | Multifamily
Fair Value Inputs, Quantitative Information [Line Items]
Mortgage loans	27,000,000	23,000,000
Significant Unobservable Inputs (Level 3) | Nonrecurring | Appraisal | Single-Family
Fair Value Inputs, Quantitative Information [Line Items]
Acquired property, net	65,000,000	73,000,000
Significant Unobservable Inputs (Level 3) | Nonrecurring | Appraisal | Multifamily
Fair Value Inputs, Quantitative Information [Line Items]
Mortgage loans	3,000,000	37,000,000
Significant Unobservable Inputs (Level 3) | Nonrecurring | Broker Price Opinion | Multifamily
Fair Value Inputs, Quantitative Information [Line Items]
Mortgage loans	614,000,000	118,000,000
Significant Unobservable Inputs (Level 3) | Nonrecurring | Accepted Offer | Single-Family
Fair Value Inputs, Quantitative Information [Line Items]
Acquired property, net	17,000,000	13,000,000
Significant Unobservable Inputs (Level 3) | Nonrecurring | Walk Forward | Single-Family
Fair Value Inputs, Quantitative Information [Line Items]
Acquired property, net	91,000,000	37,000,000
Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	46,898,000,000	83,581,000,000
Available-for-sale	0	0
Mortgage loans held for sale, at lower of cost or fair value	0	0
Total nonrecurring assets at fair value	79,889,000,000	148,112,000,000
Mortgage loans	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	46,898,000,000	83,581,000,000
Available-for-sale	0	0
Total nonrecurring assets at fair value	46,898,000,000	83,831,000,000
Mortgage loans	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) | Nonrecurring
Fair Value Inputs, Quantitative Information [Line Items]
Total nonrecurring assets at fair value	0	0
Significant Other Observable Inputs (Level 2)
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	3,184,000,000	4,568,000,000
Available-for-sale	62,000,000	84,000,000
Mortgage loans held for sale, at lower of cost or fair value	48,000,000	178,000,000
Total nonrecurring assets at fair value	3,512,490,000,000	3,875,259,000,000
Mortgage loans	3,437,979,000,000	3,796,917,000,000
Significant Other Observable Inputs (Level 2) | Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	3,184,000,000	4,568,000,000
Available-for-sale	62,000,000	84,000,000
Total nonrecurring assets at fair value	6,648,000,000	9,117,000,000
Mortgage loans	3,102,000,000	4,209,000,000
Significant Other Observable Inputs (Level 2) | Nonrecurring
Fair Value Inputs, Quantitative Information [Line Items]
Mortgage loans held for sale, at lower of cost or fair value	30,000,000	38,000,000
Other liabilities, fair value	0	0
Mortgage-related securities | Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	3,211,000,000	4,606,000,000
Mortgage-related securities | Significant Unobservable Inputs (Level 3) | Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	47,000,000	57,000,000
Mortgage-related securities | Significant Unobservable Inputs (Level 3) | Recurring | Various
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	47,000,000	57,000,000
Mortgage-related securities | Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	0	0
Mortgage-related securities | Significant Other Observable Inputs (Level 2) | Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Trading securities	3,164,000,000	4,549,000,000
Agency | Significant Unobservable Inputs (Level 3) | Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale		431,000,000
Agency | Significant Unobservable Inputs (Level 3) | Recurring | Various
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale		52,000,000
Agency | Significant Unobservable Inputs (Level 3) | Recurring | Consensus
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale	371,000,000	379,000,000
Other | Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale	270,000,000	330,000,000
Other | Significant Unobservable Inputs (Level 3) | Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale	263,000,000	322,000,000
Other | Significant Unobservable Inputs (Level 3) | Recurring | Various
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale	25,000,000	53,000,000
Other | Significant Unobservable Inputs (Level 3) | Recurring | Discounted Cash Flow
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale	$ 142,000,000	$ 175,000,000
Other | Significant Unobservable Inputs (Level 3) | Recurring | Discounted Cash Flow | Minimum | Default rate
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale, measurement input	0.05310	0.04090
Other | Significant Unobservable Inputs (Level 3) | Recurring | Discounted Cash Flow | Maximum | Default rate
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale, measurement input	0.05820	0.04340
Other | Significant Unobservable Inputs (Level 3) | Recurring | Discounted Cash Flow | Weighted average | Default rate
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale, measurement input	0.05577	0.04220
Other | Significant Unobservable Inputs (Level 3) | Recurring | Single Vendor
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale	$ 96,000,000	$ 94,000,000
Other | Significant Unobservable Inputs (Level 3) | Recurring | Single Vendor | Minimum
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale, measurement input		0.00093
Other | Significant Unobservable Inputs (Level 3) | Recurring | Single Vendor | Maximum
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale, measurement input		0.00494
Other | Significant Unobservable Inputs (Level 3) | Recurring | Single Vendor | Weighted average
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale, measurement input		0.00272
Other | Quoted Prices in Active Markets for Identical Assets (Level 1) | Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale	0	$ 0
Other | Significant Other Observable Inputs (Level 2) | Recurring
Fair Value Inputs, Quantitative Information [Line Items]
Available-for-sale	$ 7,000,000	$ 8,000,000