Loans - Narrative (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2022 USD ($) loan	Mar. 31, 2021 loan	Dec. 31, 2021 USD ($) loan	Dec. 31, 2020 USD ($) loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchase credit deteriorated loans	$ 3,607,374,000		$ 2,967,247,000
Interest income on non-accrual loans	20,000		80,000
Troubled debt restructurings	102,000		104,000
Allowance for troubled debt restructurings	0		0
Additional lending amount to customers whose loan terms has been modified in troubled debt restructuring	$ 0		0
Number of loans modified as troubled debt restructurings | loan	0	0
Number of loans modified as troubled debt restructuring subsequently defaulted | loan	0	0
Threshold amount to individually classify loans by credit risk	$ 250,000
PCD Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchase credit deteriorated loans	$ 37,895,000		$ 9,861,000
Commercial Real Estate Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of commercial real estate loans | loan	1		1
Principal amount of commercial real estate loan	$ 3,500,000		$ 3,500,000
PPP
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan interest rate	1.00%
Maturities of loans originated under first round (in years)	2 years
Maturities of loans originated under second round (in years)	5 years
Loans outstanding originated under first round				$ 351,260,000
Fees on loans originated under first round				$ 12,024,000
Number of loans originated under first round | loan				3,070
Forgiven loans originated under first round	$ 350,529,000
Net processing fees recognized on loans originated under first round	12,022,000
Loans outstanding originated under second round			157,042,000
Fees on loans originated during second round			$ 9,022,000
Number of loans originated under second round | loan			2,601
Forgiven loans originated during second round	150,850,000
Net processing fees recognized on loans originated under second round	8,713,000
Loans outstanding	6,923,000
Remaining fees on loans outstanding	$ 311,000