Fair Value Measurements - Recurring (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2025	Dec. 31, 2024
Available-for-sale securities [Member]
Fair Value
Investment maturity	10 years
Fair Value, Recurring [Member]
Fair Value
Total assets measured at fair value	$ 706	$ 571
Fair Value, Recurring [Member] | Quoted Prices in Active Markets (Level 1) [Member]
Fair Value
Cash equivalents and money market funds	79	56
Fair Value, Recurring [Member] | Quoted Prices in Active Markets (Level 1) [Member] | Equity securities [Member]
Fair Value
Investments	83	70
Fair Value, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member] | Available-for-sale securities [Member]
Fair Value
Investments	$ 544	$ 445