Accrued Expenses - Summary of Other Accrued Expenses (Detail) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Payables and Accruals [Abstract]
Professional liability risks	$ 477	$ 457
Defined contribution benefit plan	547	528
Right-of-use operating lease	379	350
Taxes other than income	343	325
Interest	315	368
Government stimulus refund liability	83
Other	1,096	904
Other accrued expenses	$ 3,240	$ 2,932