Benefit Plans - Summary of Company's Restricted Stock Units Activity (Detail) - Restricted Stock Units [Member] - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Beginning Balance	187,408	217,408	225,970
Number of Shares, granted	92,320	95,028	116,326
Number of Shares, vested	(86,402)	(114,274)	(116,242)
Number of Shares, cancelled/forfeited/expired	(21,649)	(10,754)	(8,646)
Number of Shares, Ending Balance	171,677	187,408	217,408
Weighted-Average Grant Date Fair Value, Beginning Balance	$ 76.74	$ 67.63	$ 57.06
Weighted-Average Grant Date Fair Value, granted	103.56	77.79	72.75
Weighted-Average Grant Date Fair Value, vested	50.98	58.30	53.32
Weighted-Average Grant Date Fair Value, cancelled/forfeited/expired	82.69	70.10	52.78
Weighted-Average Grant Date Fair Value, Ending Balance	$ 92.18	$ 76.74	$ 67.63
Aggregate Intrinsic Value	$ 27.4