Schedule V - Valuation And Qualifying Accounts (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022		Dec. 31, 2021	Dec. 31, 2020
Reserve Deducted From Accounts Receivable
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period		$ 14		$ 14	$ 13
Additions Charged to costs and expenses		11		4	7
Additions Charged to other accounts		0		0	0
Deductions from reserve		4	[1]	4	6
Balance at end of period		21		14	14
Reserve For Known And Incurred But Not Reported Claims
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period		1,284		1,178	1,063
Additions Charged to costs and expenses		486		589	580
Additions Charged to other accounts		(11)		(1)	6
Deductions from reserve	[2]	434		482	471
Balance at end of period		1,325		1,284	1,178
Reserve deducted from notes receivable
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period		0
Additions Charged to costs and expenses		28
Additions Charged to other accounts		0
Deductions from reserve		21
Balance at end of period		7		0
Reserve Deducted From Deferred Income Taxes
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at beginning of period		8		9	10
Additions Charged to costs and expenses		0		0	0
Additions Charged to other accounts		0		0	0
Deductions from reserve		1		1	1
Balance at end of period		$ 7		$ 8	$ 9

[1] Amount represents accounts written off, net of recoveries.

[2] Amount represents claim payments, net of recoveries.