Schedule I - Condensed Statements of Cash Flows (Parent Company Only) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
NET INCOME	$ 528,064	$ 402,461	$ 286,500
CASH FLOWS FROM FINANCING ACTIVITIES:
Class A common stock dividends	(195,944)	(196,598)	(254,924)
Cash and cash equivalents, January 1	1,389,876	1,231,593
Cash and cash equivalents, December 31	1,465,022	1,389,876	1,231,593
Parent Company [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
NET INCOME	528,064	402,461	286,500
Adjustments to reconcile net income to net cash provided by operating activities:
Equity in earnings of subsidiaries	(410,550)	(274,461)	(153,450)
Dividends received from subsidiaries	69,500	42,400	88,400
Changes in due to/from subsidiaries	9,655	23,941	32,058
Changes in other operating assets and liabilities	30	(24)	14
Net cash provided by operating activities	196,699	194,317	253,522
CASH FLOWS FROM FINANCING ACTIVITIES:
Class A common stock dividends	(195,944)	(196,598)	(254,924)
Net cash used in financing activities	(195,944)	(196,598)	(254,924)
Net increase (decrease) in cash and cash equivalents	755	(2,281)	(1,402)
Cash and cash equivalents, January 1	453	2,734	4,136
Cash and cash equivalents, December 31	$ 1,208	$ 453	$ 2,734