Allowance for Credit Losses - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss	$ 60,389,000	$ 57,839,000	$ 60,389,000	$ 57,839,000	$ 67,252,000	$ 71,124,000	$ 48,884,000	$ 40,003,000
Financing receivable, collectively evaluated for impairment	5,962,239,000		5,962,239,000			5,979,260,000
Financing receivable, allowance for credit losses, collectively evaluated for impairment	59,400,000		59,400,000			69,769,000
Financing receivable, individually evaluated for impairment and acquired with deteriorated credit quality	26,600,000		26,600,000
Financing receivable, allowance for credit losses, individually evaluated for impairment and acquired with deteriorated credit quality	1,000,000.0		1,000,000.0
Accrued interest receivable on loans	14,300,000		14,300,000			16,100,000
Loans sold	5,000,000.0		15,100,000
Charge-offs	1,861,000	141,000	3,132,000	624,000
Debt securities, available-for-sale, allowance for credit loss	21,000		21,000			2,000
Debt Securities, Held-to-maturity, Allowance for Credit Loss	137,000		137,000			0
Debt Securities, Available-for-sale, Allowance for Credit Loss, Period Increase (Decrease)	(123,000)		19,000
Debt Securities, Held-to-maturity, Credit Loss Expense (Reversal)	137,000			137,000
Debt securities, accrued interest after allowance for credit loss	4,100,000		4,100,000			3,300,000
Off-balance sheet, credit loss, liability	1,900,000		1,900,000			$ 2,600,000
Off-balance sheet, credit loss, liability, credit loss expense (reversal)	(659,000)	$ 0	(635,000)	$ 210,000
Financing Receivable, Sale, Write-off	$ 75,000		$ 1,200,000
Cumulative Effect, Period of Adoption, Adjustment
Financing Receivable, Allowance for Credit Loss [Line Items]
Allowance for credit loss								6,700,000
Debt securities, allowance for credit loss								30,000
Off-balance sheet, credit loss, liability								$ 489,000