Loans and Allowance for Credit Losses for Loans - Summary of Activity in Allowance for Loan Losses (Details) - USD ($) $ in Thousands		3 Months Ended			9 Months Ended
	Apr. 01, 2022	Sep. 30, 2022	Jun. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Allowance for loan losses:
Beginning balance		$ 468,819		$ 339,324	$ 359,202	$ 340,243
Allowance for purchase credit deteriorated (PCD) loans	$ 70,319				70,319
Loans charged-off		(9,995)		(2,019)	(17,857)	(23,193)
Charged-off loans recovered		15,605		1,726	21,197	7,479
Net recoveries (charge-offs)		5,610		(293)	3,340	(15,714)
Provision (credit) for loan losses		1,315		3,496	42,883	17,998
Ending balance		475,744	$ 468,819	342,527	475,744	342,527
Charge-offs	$ 62,400		62,400
Commercial and industrial
Allowance for loan losses:
Beginning balance		144,539		109,689	103,090	131,070
Allowance for purchase credit deteriorated (PCD) loans					33,452
Loans charged-off		(5,033)		(1,248)	(11,144)	(19,283)
Charged-off loans recovered		13,236		514	16,012	2,781
Net recoveries (charge-offs)		8,203		(734)	4,868	(16,502)
Provision (credit) for loan losses		1,309		(5,078)	12,641	(10,691)
Ending balance		154,051	144,539	103,877	154,051	103,877
Commercial Real Estate
Allowance for loan losses:
Beginning balance		277,227		189,139	217,490	164,113
Allowance for purchase credit deteriorated (PCD) loans					36,618
Loans charged-off		(4,000)		0	(4,173)	(382)
Charged-off loans recovered		1,729		29	2,060	763
Net recoveries (charge-offs)		(2,271)		29	(2,113)	381
Provision (credit) for loan losses		(7,176)		10,553	15,785	35,227
Ending balance		267,780	277,227	199,721	267,780	199,721
Residential Mortgage
Allowance for loan losses:
Beginning balance		29,889		25,303	25,120	28,873
Allowance for purchase credit deteriorated (PCD) loans					206
Loans charged-off		0		0	(27)	(139)
Charged-off loans recovered		163		228	694	576
Net recoveries (charge-offs)		163		228	667	437
Provision (credit) for loan losses		6,105		(799)	10,164	(4,578)
Ending balance		36,157	29,889	24,732	36,157	24,732
Consumer
Allowance for loan losses:
Beginning balance		17,164		15,193	13,502	16,187
Allowance for purchase credit deteriorated (PCD) loans					43
Loans charged-off		(962)		(771)	(2,513)	(3,389)
Charged-off loans recovered		477		955	2,431	3,359
Net recoveries (charge-offs)		(485)		184	(82)	(30)
Provision (credit) for loan losses		1,077		(1,180)	4,293	(1,960)
Ending balance		$ 17,756	$ 17,164	$ 14,197	$ 17,756	$ 14,197