Shareholders' Equity - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Feb. 25, 2021	Dec. 31, 2020
Class of Stock [Line Items]
Cash dividends received	$ 7,772,000	$ 26,754,000
Repurchase of common stock	10,000	17,295,000
Market value of shares repurchased under equity compensation plans	$ 2,000	$ 148,000
Employee Stock
Class of Stock [Line Items]
Company's common stock in lieu of cash to exercise options to purchase shares (in shares)	0	4,668
Other Share Based Awards
Class of Stock [Line Items]
Company's common stock in lieu of cash to exercise options to purchase shares (in shares)	70	133
2021 Stock Repurchase Plan
Class of Stock [Line Items]
Repurchase of common stock (in shares)			2,000,000
Stock repurchase program, percentage of common stock			6.70%
Repurchase of common stock (in shares)	0
2019 Stock Repurchase Plan
Class of Stock [Line Items]
Repurchase of common stock (in shares)	223
Repurchase of common stock	$ 8,260
Cumulative number of shares repurchased (in shares)				858,717
Common Stock
Class of Stock [Line Items]
Repurchase of common stock (in shares)	293	558,670
Repurchase of common stock	$ 5,000	$ 9,962,000
Market value of shares repurchased under equity compensation plans	$ 2,500	$ 153,000