Premises and Equipment - Narrative (Details)	12 Months Ended
	Dec. 31, 2023 USD ($) property	Dec. 31, 2022 USD ($) property	Dec. 31, 2021 USD ($) property
Property, Plant and Equipment [Line Items]
Depreciation	$ 10,500,000	$ 10,700,000	$ 11,600,000
Number of properties transferred to held for sale | property	0	0	5
Number of properties sold | property	0	5	3
Proceeds from sale of bank premises and equipment	$ 0	$ 17,313,000	$ 21,981,000
Gain (loss) on disposition of property plant equipment	$ 0	$ 1,412,000	(4,715,000)
Properties transferred to held for sale, amount			37,600,000
Loss on properties transferred to held for sale			$ 1,200,000
Disposal Group, Held-for-sale or Disposed of by Sale, Not Discontinued Operations
Property, Plant and Equipment [Line Items]
Number of properties sold | property			1
Gain (loss) on disposition of property plant equipment			$ 0
Century Bancorp, Inc.
Property, Plant and Equipment [Line Items]
Number of properties transferred to held for sale | property			4
Number of properties sold | property		4	2