Fair Value Measurements (Fair Value of Note Payable and Long-Term Debt) (Detail) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of note payable	$ 25	$ 25
Total	860	868
6.900% Senior Debentures, Due 2028
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of senior debt	$ 29	$ 29
Interest rate	6.90%	6.90%
6.920% Senior Debentures, Due 2028
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of senior debt	$ 416	$ 420
Interest rate	6.92%	6.92%
6.125% Senior Notes, Due 2034
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of senior debt	$ 390	$ 394
Interest rate	6.125%	6.125%
Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of note payable	$ 0	$ 0
Total	0	0
Level 1 \| 6.900% Senior Debentures, Due 2028
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of senior debt	0	0
Level 1 \| 6.920% Senior Debentures, Due 2028
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of senior debt	0	0
Level 1 \| 6.125% Senior Notes, Due 2034
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of senior debt	0	0
Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of note payable	25	25
Total	860	868
Level 2 \| 6.900% Senior Debentures, Due 2028
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of senior debt	29	29
Level 2 \| 6.920% Senior Debentures, Due 2028
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of senior debt	416	420
Level 2 \| 6.125% Senior Notes, Due 2034
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of senior debt	390	394
Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of note payable	0	0
Total	0	0
Level 3 \| 6.900% Senior Debentures, Due 2028
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of senior debt	0	0
Level 3 \| 6.920% Senior Debentures, Due 2028
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of senior debt	0	0
Level 3 \| 6.125% Senior Notes, Due 2034
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis
Fair value of senior debt	$ 0	$ 0

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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