Share-based Compensation - Summary of SARs Activity (Detail) - Stock-Settled SARs Activity	3 Months Ended
	Mar. 31, 2021 $ / shares shares
Shares
Outstanding, beginning balance (in shares) | shares	140,155
Exercised (in shares) | shares	(80,571)
Expired or forfeited (in shares) | shares	0
Outstanding, ending balance (in shares) | shares	59,584
Weighted-Average Exercise Price
Outstanding, beginning balance (in dollars per share) | $ / shares	$ 35.98
Exercised (in dollars per share) | $ / shares	34.59
Expired or forfeited (in dollars per share) | $ / shares	0
Outstanding, ending balance (in dollars per share) | $ / shares	$ 37.85