Casualty, Environmental and Other Reserves - Schedule of Claims Activity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Loss Contingency Accrual [Roll Forward]
Balance at beginning of period	$ 368	$ 314	$ 305
Charged to Expense	143	130	107
Payments	(130)	(138)	(98)
Balance end of period	436	368	314
Quality Carriers, Inc.
Loss Contingency Accrual [Roll Forward]
Assumed in acquisition		62
Pan-Am
Loss Contingency Accrual [Roll Forward]
Assumed in acquisition	55
Casualty Reserves
Loss Contingency Accrual [Roll Forward]
Balance at beginning of period	180	196	187
Charged to Expense	45	55	55
Payments	(50)	(71)	(46)
Balance end of period	194	180	196
Casualty Reserves | Quality Carriers, Inc.
Loss Contingency Accrual [Roll Forward]
Assumed in acquisition		0
Casualty Reserves | Pan-Am
Loss Contingency Accrual [Roll Forward]
Assumed in acquisition	19
Environmental Reserves
Loss Contingency Accrual [Roll Forward]
Balance at beginning of period	108	76	74
Charged to Expense	47	26	20
Payments	(30)	(23)	(18)
Balance end of period	161	108	76
Environmental Reserves | Quality Carriers, Inc.
Loss Contingency Accrual [Roll Forward]
Assumed in acquisition		29
Environmental Reserves | Pan-Am
Loss Contingency Accrual [Roll Forward]
Assumed in acquisition	36
Other Reserves
Loss Contingency Accrual [Roll Forward]
Balance at beginning of period	80	42	44
Charged to Expense	51	49	32
Payments	(50)	(44)	(34)
Balance end of period	81	80	$ 42
Other Reserves | Quality Carriers, Inc.
Loss Contingency Accrual [Roll Forward]
Assumed in acquisition		$ 33
Other Reserves | Pan-Am
Loss Contingency Accrual [Roll Forward]
Assumed in acquisition	$ 0