Stock-Based Compensation - Summary of Stock-Based Compensation Grants (Detail)	9 Months Ended
	Sep. 30, 2020 $ / shares shares
Time Based Restricted Stock Units [Member]
Stock Awards Granted | shares	54,126
Weighted-Average Grant Price Per Share | $ / shares	$ 53.87
Performance Based Restricted Stock Units [Member]
Stock Awards Granted | shares	78,404	[1]
Weighted-Average Grant Price Per Share | $ / shares	$ 39.60	[1]
Stock Appreciation Rights [Member]
Stock Awards Granted | shares	43,830
Weighted-Average Grant Price Per Share | $ / shares	$ 50.39

[1] Includes 54,024 of target performance-based restricted stock unit awards granted during the nine months ended September 30, 2020, and adjustments of (5,124), 6,058 and 23,446 to grants due to the actual performance level achieved for restricted stock and restricted stock units awarded in 2019, 2018, and 2017, respectively.