Shareholders' Equity (Detail) $ / shares in Units, $ in Millions					3 Months Ended
	Mar. 15, 2023 USD ($)	Feb. 15, 2023 $ / shares	Mar. 15, 2022 USD ($)	Feb. 16, 2022 $ / shares	Mar. 31, 2023 USD ($) $ / shares shares	Mar. 31, 2022 $ / shares shares	Dec. 31, 2022 $ / shares	May 03, 2016 USD ($)
Class of Stock [Line Items]
Preferred shares par value (in dollars per share)					$ 1.00		$ 1.00
Liquidation preference (in dollars per share)					25,000		$ 25,000
Depositary shares, dividends per share (in dollars per share)		$ 0.43750		$ 0.43750
Fractional interest per one preference share		0.001		0.001
Payments of dividends | $			$ 10.8
Dividend declared per common share (in dollars per share)				$ 0.31	$ 0	$ 0.31
Number of shares repurchased (in shares) | shares					0	0
Series A Preferred Stock
Class of Stock [Line Items]
Preferred stock, dividends declared (in dollars per share)		$ 437.50		$ 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
Payments of dividends | $	$ 2.6		$ 2.6
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