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Fair Value Measurements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Book Value | Retail
Financial Instruments
Long-term debt	$ 1,500	$ 1,500
Book Value | Institutional
Financial Instruments
Long-term debt	536	536
Book Value | Other
Financial Instruments
Long-term debt	1,063	1,208
Fair Value | Level 2 | Retail
Financial Instruments
Long-term debt	1,097	899
Fair Value | Level 2 | Institutional
Financial Instruments
Long-term debt	451	395
Fair Value | Level 2 | Other
Financial Instruments
Long-term debt	$ 1,063	$ 1,208
6.7% Senior Notes
Financial Instruments
Interest rate on debt	6.70%
Interest rate | Minimum | Institutional and Other
Financial Instruments
Fair value assumption, interest rate	6.48%	5.38%
Interest rate | Maximum | Institutional and Other
Financial Instruments
Fair value assumption, interest rate	7.96%	8.28%

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Contractual interest rate for funds borrowed, under the debt agreement.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

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-Name Accounting Standards Codification
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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
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