Loans - Narrative (Details) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021 USD ($) contract	Mar. 31, 2020 USD ($) contract	Dec. 31, 2020 USD ($)
Financing Receivable, Troubled Debt Restructuring [Line Items]
Net deferred costs			$ 22,600
Accrued interest receivable	$ 20,900		25,800
Interest income from securities with no related allowance	200	$ 300
Value of loans deferred, not classified as TDRs	$ 28,408		74,062
Percentage on payment deferral	0.60%
Allowance for credit loss on TDRs	$ 200	$ 100
Number of loans under trouble debt restructuring | contract	0	3
Amount of loans in default		$ 1,400
Interest income related to impaired loans with impairment measured on present value of expected future cash flows	$ 5	$ 24
Maximum
Financing Receivable, Troubled Debt Restructuring [Line Items]
Value of loans deferred, not classified as TDRs	$ 1,100,000
Percentage on payment deferral	21.00%
Portfolio Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Net deferred costs	$ 23,800
Portfolio Loans | Paycheck Protection Program
Financing Receivable, Troubled Debt Restructuring [Line Items]
Net deferred fees	13,500		9,500
Loans
Financing Receivable, Troubled Debt Restructuring [Line Items]
Remaining fair value adjustment for loans acquired	$ 27,300		$ 30,200
Percentage of fair value adjustment for loans acquired	2.90%		2.90%