Lease Commitments - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($)
Operating Leased Assets [Line Items]
Impairment of right-of-use	$ 21
Minimum
Operating Leased Assets [Line Items]
Operating lease, renewal term	1 year
Maximum
Operating Leased Assets [Line Items]
Operating lease, renewal term	20 years