Investments in Securities - Available-for-sale Securities 1 (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale [Line Items]
Total Amortized Cost	$ 695	$ 714
Allowance for Credit Losses	(3)	(3)
Gross Unrealized Gains in AOCI	11	8
Gross Unrealized Losses in AOCI	(24)	(23)
Total Fair Value	679	696
Agency securities
Debt Securities, Available-for-sale [Line Items]
Total Amortized Cost	435	445
Allowance for Credit Losses	0	0
Gross Unrealized Gains in AOCI	3	3
Gross Unrealized Losses in AOCI	(24)	(22)
Total Fair Value	414	426
Other mortgage-related securities
Debt Securities, Available-for-sale [Line Items]
Total Amortized Cost	260	269
Allowance for Credit Losses	(3)	(3)
Gross Unrealized Gains in AOCI	8	5
Gross Unrealized Losses in AOCI	0	(1)
Total Fair Value	$ 265	$ 270

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27161-111563

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27161-111563

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Amount excluding accrued interest, of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

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Amortized cost excluding accrued interest, before allowance for credit loss, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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-URI https://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

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