Schedule II. Condensed Financial Information of Registrant (Notes To Condensed Financial Statements) (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Condensed Financial Statements, Captions [Line Items]
Stock-based compensation not involving cash	$ 30,272	$ 35,892	$ 44,843
Interest paid	83,072	83,518	81,723
Income taxes paid (received)	$ 96,218	$ 76,701	101,982
Preferred stock, shares outstanding (in shares)	0	0
Parent Company
Condensed Financial Statements, Captions [Line Items]
Cash dividends from subsidiaries	$ 478,535	$ 485,871	479,988
Stock-based compensation not involving cash	30,272	35,892	44,843
Contribution of property to subsidiary	5,004	0	0
Interest paid	86,206	86,504	86,868
Income taxes paid (received)	$ (11,838)	$ (12,744)	$ (16,617)
Preferred stock, liquidation distribution available to stockholders, per share in thousands (in dollars per share)	$ 1,000
Preferred stock, liquidating distribution legally available, aggregate value	$ 351,000
Cumulative Series A Preferred Stock | Parent Company
Condensed Financial Statements, Captions [Line Items]
Preferred stock, shares issued (in shares)	351,000
Preferred stock, shares outstanding (in shares)	351,000
6.50% Cumulative Preferred Stock, Series A | Parent Company
Condensed Financial Statements, Captions [Line Items]
Preferred stock, shares issued (in shares)	280,000
Preferred stock, shares outstanding (in shares)	280,000
Preferred stock, dividend rate, percentage	6.50%
7.15% Cumulative Preferred Stock, Series A | Parent Company
Condensed Financial Statements, Captions [Line Items]
Preferred stock, shares issued (in shares)	71,000
Preferred stock, shares outstanding (in shares)	71,000
Preferred stock, dividend rate, percentage	7.15%