Loans - Additional Information (Details) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021		Dec. 31, 2020		Dec. 31, 2019		Jan. 31, 2020
Anticipated credit losses	$ 2,816,000	$ 1,594,000	$ (3,631,000)	$ (7,512,000)	$ (6,158,000)	$ 3,658,000	$ 1,868,000	$ 43,786,000	$ (6,733,000)	[1]	$ 43,154,000	[1]	$ 2,905,000	[1]
Loan balance	5,767,039,000				5,847,484,000				5,767,039,000		5,847,484,000
Loans and Leases Receivable, Loans in Process	477,890,000				355,065,000				477,890,000		355,065,000
Purchase Credit Impaired [Member]
Loan balance	615,000								615,000
Loan Purchase [Member]
Purchase price of loans at acquisition	2,200,000,000				2,221,204,000				2,200,000,000		2,221,204,000
Fair value of purchase price of loans at acquisition					2,247,317,000						2,247,317,000				$ 79,100,000
Financing receivable credit discount															7,700,000
Financing receivable non credit discount															$ 4,100,000
Loan balance	32,337,000				65,801,000				32,337,000		65,801,000
Scenario Plan [Member]
Anticipated credit losses									5,000,000.0
Consumer Portfolio Segment
Loans and Leases Receivable, Loans in Process	3,300,000				784,000				3,300,000		784,000
Unfunded Loan Commitments [Member]
Unfunded loan commitments	1,400,000,000								1,400,000,000
COVID-19 [Member] | PPP [Member]
Cash paid for paycheck protection program									450,000,000
COVID-19 [Member] | PPP [Member] | Other Loans [Member] | Commercial Loan Portfolio Segment [Member]
Loans outstanding	58,900,000				386,900,000				58,900,000		386,900,000
TDRs [Member]
Financing Receivable, Modifications, Recorded Investment	11,900,000				16,600,000				11,900,000		16,600,000
Specified Reserves, Provision for Troubled Debt Restructurings	378,000				883,000				378,000		883,000
Loans and Leases Receivable, Impaired, Commitment to Lend	$ 348,000				303,000				348,000		303,000
Loans receivable deferred					53,450,000						53,450,000
Financing Receivables, Impaired, Troubled Debt Restructuring, Write-down									4,200,000
Financing Receivable, Allowance, Period Increase (decrease)									21,000		660,000		34,000
TDRs [Member] | Subsequently Defaulted [Member]
Financing Receivable, Allowance, Period Increase (decrease)									$ 1,000		5,000		$ 4,000
TDRs [Member] | Minimum [Member]
Loans receivable deferred					$ 53,500,000						$ 53,500,000

[1] Beginning January 1, 2020, calculation is based on current expected loss methodology. Prior to January 1, 2020, calculation was based on incurred loss methodology.