Business Combinations (Details) $ in Thousands	Aug. 01, 2024 USD ($) branch shares	Sep. 30, 2025 USD ($)	Dec. 31, 2024 USD ($)	Sep. 30, 2024 USD ($)
Business Combination [Line Items]
Total assets at period end		$ 69,629,638	$ 64,879,668	$ 63,788,424
Deposits		$ 56,711,381	$ 52,512,349	$ 51,404,966
Macatawa Bank Corporation
Business Combination [Line Items]
Total assets at period end	$ 2,900,000
Deposits	2,300,000
Loan	$ 1,300,000
Macatawa Bank Corporation
Business Combination [Line Items]
Business acquisition, number of shares issued (in shares) | shares	4,700,000
Fair value of consideration paid	$ 499,300
Business combination, number of acquired operating branches | branch	26
Business combination, discount on acquired loans	$ 53,700
Business combination, discount on securities	33,500
Business combination, intangible assets acquired	$ 253,000
Macatawa Bank Corporation | Macatawa Bank Corporation
Business Combination [Line Items]
Number of common stock shares issued for each share of acquiree stock (in shares) | shares	0.137