Investment Securities - Narrative (Details)	3 Months Ended		8 Months Ended	9 Months Ended
	Sep. 30, 2023 USD ($) security	Sep. 30, 2022 USD ($)	Sep. 01, 2022 USD ($)	Sep. 30, 2023 USD ($) security	Sep. 30, 2022 USD ($)	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2021 USD ($)
Debt Securities, Available-for-sale [Line Items]
Available-for-sale securities, accrued interest receivable	$ 2,200,000			$ 2,200,000			$ 2,600,000
Held-to-maturity securities, accrued interest receivable	2,000,000			2,000,000			1,900,000
Held-to-maturity, book value			$ 511,000,000
Fair Value	385,065,000		477,000,000	385,065,000			411,264,000
Available-for-sale to held-to-maturity, transfer unrealized loss			$ 34,000,000
Proceeds from sales of investment securities, available-for-sale		$ 44,100,000		0	$ 47,175,000
Gross realized gains on securities		0			24,000
Gross realized losses on securities	$ 96,000			$ 96,000
Number of available for sale securities that have unrealized losses | security	282			282
Number of held to maturity securities that have unrealized losses | security	159			159
Allowance for credit loss	$ 17,368,000	$ 15,182,000		$ 17,368,000	$ 15,182,000	$ 17,066,000	16,128,000	$ 13,963,000	$ 12,910,000
Investment Securities
Debt Securities, Available-for-sale [Line Items]
Allowance for credit loss	0			0
Asset Pledged as Collateral
Debt Securities, Available-for-sale [Line Items]
Investment securities pledged as collateral	$ 394,000,000			$ 394,000,000			$ 541,800,000