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Fair Value Measurements (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Book Value | Retail
Financial Instruments
Long-term debt	$ 1,500	$ 1,917
Book Value | Institutional
Financial Instruments
Long-term debt	535	535
Book Value | Other
Financial Instruments
Long-term debt	746	106
Fair Value | Level 2 | Retail
Financial Instruments
Long-term debt	1,594	1,962
Fair Value | Level 2 | Institutional
Financial Instruments
Long-term debt	659	707
Fair Value | Level 2 | Other
Financial Instruments
Long-term debt	$ 746	$ 106
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	1.31%	1.35%
Interest rate | Maximum | Institutional and Other
Financial Instruments
Fair value assumption, interest rate	4.40%	3.75%

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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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
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