Loans and Leases (Allowance For Loan And Lease Losses By Portfolio Segment) (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Jan. 31, 2022	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period				$ 301,187	$ 359,431
Initial allowance for PCD loans and leases				88,045	0
Provision (benefit)		$ 31,352	$ 7,898	232,148	(39,435)
Charge-offs				(64,830)	(16,473)
Recoveries				17,775	11,399
Balance, end of period		574,325	314,922	574,325	314,922
ALLL, Individually evaluated for impairment		49,672	12,099	49,672	12,099
ALLL, Collectively evaluated for impairment		524,653	302,823	524,653	302,823
PCD loans | Sterling
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Charge-offs	$ (48,300)
Commercial
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period				257,877	312,244
Initial allowance for PCD loans and leases				78,376	0
Provision (benefit)		34,513	7,681	230,881	(37,049)
Charge-offs				(61,361)	(8,638)
Recoveries				10,542	2,614
Balance, end of period		516,315	269,171	516,315	269,171
ALLL, Individually evaluated for impairment		36,394	7,791	36,394	7,791
ALLL, Collectively evaluated for impairment		479,921	261,380	479,921	261,380
Consumer
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period				43,310	47,187
Initial allowance for PCD loans and leases				9,669	0
Provision (benefit)		(3,161)	217	1,267	(2,386)
Charge-offs				(3,469)	(7,835)
Recoveries				7,233	8,785
Balance, end of period		58,010	45,751	58,010	45,751
ALLL, Individually evaluated for impairment		13,278	4,308	13,278	4,308
ALLL, Collectively evaluated for impairment		$ 44,732	$ 41,443	$ 44,732	$ 41,443