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Premises and Equipment (Details) - USD ($)	12 Months Ended
Premises and Equipment (Details) - USD ($)	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Premises and equipment
Total	$ 819,265,000	$ 844,031,000
Less accumulated depreciation	(298,630,000)	(285,532,000)
Net premises and equipment	520,635,000	558,499,000
Depreciation expense charged to operations	29,400,000	29,200,000	$ 25,300,000
2018-15
Premises and equipment
Capitalized implementation costs related to internal use software	0
Land
Premises and equipment
Total	133,105,000	145,276,000
Buildings and leasehold improvements
Premises and equipment
Total	$ 395,360,000	404,655,000
Buildings and leasehold improvements \| Minimum
Premises and equipment
Useful Life	15 years
Buildings and leasehold improvements \| Maximum
Premises and equipment
Useful Life	40 years
Equipment and furnishings
Premises and equipment
Total	$ 178,676,000	169,271,000
Equipment and furnishings \| Minimum
Premises and equipment
Useful Life	3 years
Equipment and furnishings \| Maximum
Premises and equipment
Useful Life	10 years
Lease right of use assets
Premises and equipment
Total	$ 107,979,000	110,311,000
Construction in process
Premises and equipment
Total	$ 4,145,000	14,518,000
Computer software
Premises and equipment
Useful Life	36 months
Total	$ 23,200,000	43,500,000
Depreciation expense charged to operations	$ 4,900,000	$ 4,800,000	$ 2,400,000