Description of Business and Summary of Significant Accounting Policies - Allowance for Credit Losses (Detail) - shares shares in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Accounting Policies [Abstract]
Restricted stock units outstanding to purchase shares included in diluted earnings per common share (in shares)	2	2	2
Maximum threshold period for new customers	210 days
Minimum threshold period for existing customers	210 days