Shareholders' Equity - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Feb. 25, 2021	Dec. 31, 2018
Class of Stock [Line Items]
Cash dividends received	$ 31,571,000	$ 63,419,000	$ 32,669,000
Repurchase of common stock (in shares)				2,000,000
Stock repurchase plan percentage of common stock				6.70%
Stock repurchase plan, number of shares repurchased (in shares)			0
Common stock, shares outstanding (in shares)	29,730,424	29,727,214
Stock repurchase plan, amount of shares repurchased	$ 4,958,000	$ 27,069,000	$ 5,108,000
Market value of shares repurchased under equity compensation plans	$ 2,118,000	$ 736,000	$ 5,108,000
Stock options
Class of Stock [Line Items]
Company's common stock in lieu of cash to exercise options to purchase shares (in shares)	28,276	12,488	115,954
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)	19,413	12,058	15,242
Maximum
Class of Stock [Line Items]
Amount available to dividend to holding company	$ 154,466,000
2021 Stock Repurchase Plan
Class of Stock [Line Items]
Cumulative number of shares repurchased (in shares)	63,317
2019 Stock Repurchase Plan
Class of Stock [Line Items]
Cumulative number of shares repurchased (in shares)		858,717
Stock repurchase plan, number of shares repurchased (in shares)	223
Common Stock
Class of Stock [Line Items]
Stock repurchase plan, number of shares repurchased (in shares)	111,229	883,263	131,196
Common stock, shares outstanding (in shares)	29,730,424	29,727,214	30,523,824		30,417,223
Stock repurchase plan, amount of shares repurchased	$ 1,987,000	$ 15,746,000	$ 2,339,000
Market value of shares repurchased under equity compensation plans	$ 2,118,000	$ 736,000	$ 5,108,000