Shareholders Equity - Additional Information (Detail) - USD ($)					3 Months Ended
	Mar. 16, 2020	Feb. 18, 2020	Mar. 15, 2019	Feb. 20, 2019	Mar. 31, 2020	Mar. 31, 2019	May 03, 2016
Class of Stock [Line Items]
Dividends declared per common share (in dollars per share)		$ 0.31		$ 0.31	$ 0.31	$ 0.31
Cash dividends paid - common shares, total	$ 10,700,000		$ 10,800,000		$ 10,700,000	$ 10,800,000
2016 Repurchase Authorization [Member]
Class of Stock [Line Items]
Total number of shares authorized for purchase							$ 150,000,000.0
Remaining number of shares available under repurchase authorization					$ 53,300,000