Shareholders' Equity (Detail) $ / shares in Units, $ in Millions						3 Months Ended
	Mar. 15, 2022 USD ($)	Feb. 16, 2022 $ / shares	Mar. 15, 2021 USD ($)	Mar. 12, 2021 USD ($)	Feb. 12, 2021 $ / shares	Mar. 31, 2022 USD ($) $ / shares shares	Mar. 31, 2021 $ / shares	Dec. 31, 2021 $ / shares	May 03, 2016 USD ($)
Class of Stock [Line Items]
Cash dividend declared - common shares (in dollars per share)		$ 0.31			$ 0.31	$ 0.31	$ 0.31
Payments of dividends | $	$ 10.8			$ 10.8
Preferred shares par value (in dollars per share)						1.00		$ 1.00
Liquidation preference (in dollars per share)						$ 25,000		$ 25,000
Fractional interest per one preference share		0.001			0.001
Depositary shares, dividends per share (in dollars per share)		$ 0.437500			$ 0.43750
Number of shares repurchased (in shares) | shares						0
Series A Preferred Stock
Class of Stock [Line Items]
Payments of dividends | $	$ 2.6		$ 2.6
Preferred stock, dividends declared (in dollars per share)		$ 437.500			$ 437.50
Preferred stock, dividend rate (in percentage)		7.00%			7.00%
Preferred shares par value (in dollars per share)		$ 1.00			$ 1.00
Liquidation preference (in dollars per share)		$ 25,000			$ 25,000
2016 Repurchase Authorization
Class of Stock [Line Items]
Total number of shares authorized for purchase | $									$ 150.0
Remaining number of shares available under repurchase authorization | $						$ 53.3