Stock Options and Other Equity-Based Incentive Instruments - Restricted Stock Unit (RSU) Activity (Detail)	9 Months Ended
	Sep. 30, 2023 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)	139,194
RSUs granted (in shares)	84,066
RSUs added through dividend and performance credits (in shares)	3,715
RSUs released (in shares)	(72,847)
RSUs forfeited/expired (in shares)	(844)
Outstanding at end of period (in shares)	153,284
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)	114,481
RSUs granted (in shares)	66,209
RSUs added through dividend and performance credits (in shares)	0
RSUs released (in shares)	(55,928)
RSUs forfeited/expired (in shares)	(902)
Outstanding at end of period (in shares)	123,860