Condensed Financial Statements of Parent Company (Schedule of Condensed Statements of Cash Flows) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Condensed Financial Statements, Captions [Line Items]
Net income	$ 443,079	$ 331,151	$ 443,599
Stock-based compensation	12,753	13,918	15,946
Net tax benefit from stock-based compensation	7,877	852	2,447
Net cash provided by (used in) operating activities	648,293	524,243	634,090
Net cash provided by (used in) investing activities	(2,525,015)	(1,631,047)	(1,386,750)
Principal payments on long-term borrowings	(13,403)
Redemption of Series A preferred stock	0	(150,000)	0
Proceeds from issuance of Series B preferred stock	0	145,452	0
Proceeds from stock option exercises	54,417	12,557	20,770
Purchase of treasury stock	(3,864)	(15,785)	(68,793)
Treasury stock issued to 401(k) stock purchase plan	1,749	10,307	0
Cash dividends paid on preferred stock	(7,157)	(2,016)	(8,063)
Cash dividends paid on common stock	(188,786)	(180,584)	(177,006)
Net cash provided by (used in) financing activities	8,170,869	7,607,476	585,062
Parent Company [Member]
Condensed Financial Statements, Captions [Line Items]
Net income	443,079	331,151	443,599
Equity in undistributed earnings of subsidiaries	(232,727)	(42,309)	(218,190)
Stock-based compensation	700	770	780
Net tax benefit from stock-based compensation	278	370	240
Net change in other assets and other liabilities	23,890	(8,937)	22,216
Net cash provided by (used in) operating activities	235,220	281,045	248,645
Redemption of investment in non-bank subsidiary	406	0	0
Net cash provided by (used in) investing activities	406	0	0
Principal payments on long-term borrowings	(13,403)	0	0
Redemption of Series A preferred stock	0	(150,000)	0
Proceeds from issuance of Series B preferred stock	0	145,452	0
Proceeds from stock option exercises	54,417	12,557	20,770
Proceeds from stock-based compensation activities of subsidiaries	12,053	13,148	15,166
Purchase of treasury stock	(3,864)	(15,785)	(68,793)
Treasury stock issued to 401(k) stock purchase plan	1,749	10,307	0
Cash dividends paid on preferred stock	(7,157)	(2,016)	(8,063)
Cash dividends paid on common stock	(188,786)	(180,584)	(177,006)
Net cash provided by (used in) financing activities	(144,991)	(166,921)	(217,926)
Net change in cash and cash equivalents	90,635	114,124	30,719
Cash and cash equivalents at beginning of year	381,240	267,116	236,397
Cash and cash equivalents at end of year	$ 471,875	$ 381,240	$ 267,116