Summary of Nonvested Restricted Shares Activity (Detail) - Restricted Stock Units (RSUs)	12 Months Ended
	Dec. 31, 2021 $ / shares shares
GRANT DATE FAIR VALUE
Nonvested awards outstanding, beginning balance | $ / shares	$ 70.49	[1]
Granted | $ / shares	90.76	[1]
Vested | $ / shares	76.39	[1]
Forfeited | $ / shares	91.89	[1]
Nonvested awards outstanding, ending balance | $ / shares	$ 80.16	[1]
NONVESTED NUMBER OF SHARES
Nonvested awards outstanding, beginning balance | shares	142,400
Granted | shares	102,000
Vested | shares	(87,000)
Forfeited | shares	(2,900)
Nonvested awards outstanding, ending balance | shares	154,500

[1] Weighted Average