Shareholders' Equity (Narrative) (Detail) $ / shares in Units, $ in Millions	1 Months Ended				12 Months Ended
	Jan. 31, 2023 $ / shares	Jun. 30, 2022 USD ($) shares	May 31, 2020 USD ($) $ / shares shares	Jun. 30, 2015 USD ($) $ / shares shares	Dec. 31, 2023 $ / shares	Dec. 31, 2022 $ / shares	Dec. 31, 2021 $ / shares	Dec. 31, 2020 $ / shares
Temporary Equity [Line Items]
Cash dividends declared per common share (usd per share)						$ 1.36	$ 1.24	$ 1.12
Forecast
Temporary Equity [Line Items]
Cash dividends declared per common share (usd per share)					$ 1.60
Subsequent Event
Temporary Equity [Line Items]
Cash dividends declared per common share (usd per share)	$ 0.40
Series D Preferred Stock
Temporary Equity [Line Items]
Sale of stock (in shares) | shares				5,000,000
Sale of stock, proceeds | $				$ 125.0
Preferred stock, liquidation value per share (usd per share)				$ 25		$ 25	25
Preferred stock, dividend rate				6.50%
Series D Preferred Stock | London Interbank Offered Rate (LIBOR)
Temporary Equity [Line Items]
Preferred stock, dividend rate, variable spread				4.06%
Series D Preferred Stock | Secured Overnight Financing Rate (SOFR)
Temporary Equity [Line Items]
Preferred stock, dividend rate, variable spread						4.06%
Dividend rate, spread on floating rate						0.0026161
Series E Preferred Stock
Temporary Equity [Line Items]
Sale of stock (in shares) | shares			11,500
Sale of stock, proceeds | $			$ 287.5
Preferred stock, liquidation value per share (usd per share)			$ 25,000			$ 25,000	$ 25,000
Preferred stock, dividend rate			6.875%
Series E Preferred Stock | US Treasury (UST) Interest Rate
Temporary Equity [Line Items]
Dividend rate, spread on floating rate			0.06507
Depositary shares
Temporary Equity [Line Items]
Sale of stock (in shares) | shares			11,500,000
Ratio of preferred stock to depositary shares			0.001
Public Offering | Common stock
Temporary Equity [Line Items]
Sale of stock (in shares) | shares		3,450,000
Sale of stock, proceeds | $		$ 285.7