Stock Options and Other Equity-Based Incentive Instruments - Restricted Stock Unit (RSU) Activity (Detail)	3 Months Ended
	Mar. 31, 2022 shares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
RSUs released (in shares)	0
Restricted Stock Units (RSUs) | Service Condition Vesting RSUs
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at beginning of period (in shares)	103,517
RSUs granted (in shares)	21,597
RSUs added through dividend and performance credits (in shares)	0
RSUs released (in shares)	730
RSUs forfeited/expired (in shares)	0
Outstanding at end of period (in shares)	125,844
Restricted Stock Units (RSUs) | Market Plus Service Condition Vesting RSUs
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Outstanding at beginning of period (in shares)	99,763
RSUs granted (in shares)	0
RSUs added through dividend and performance credits (in shares)	0
RSUs released (in shares)	0
RSUs forfeited/expired (in shares)	0
Outstanding at end of period (in shares)	99,763