Non Purchased Loans - Narrative (Details)	3 Months Ended
	Mar. 31, 2021 USD ($) loan	Mar. 31, 2020 USD ($) loan	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Loans and Allowance for Loan Losses (Additional Textual) [Abstract]
Outstanding balance of restructured loans	$ 10,515,302,000		$ 10,757,503,000
Allowance for loan losses attributable to restructured loans	$ 173,106,000	$ 120,185,000	$ 176,144,000	$ 52,162,000
Non purchased loans and leases
Loans and Allowance for Loan Losses (Additional Textual) [Abstract]
Mortgage and commercial loans discontinued past due period	90 days
Consumer and other retail loans charged-off past due period	120 days
Nonperforming loans charged-off past due period	90 days
Number of restructured loans | loan	0	2
Restructured loans discontinued past due period	90 days	90 days
Troubled debt restructured that has subsequently defaulted	$ 0
Remaining availability under commitments to lend additional funds on restructured loans	$ 0	$ 0
Number of loan modifications | loan	4	5
Modified loans, balance	$ 1,269,000	$ 1,345,000
Non purchased loans and leases | Loan deferral | Loan Deferral Program, CARES Act
Loans and Allowance for Loan Losses (Additional Textual) [Abstract]
Initial deferral period		90 days
Second deferral period		90 days
Number of loan modifications | loan	453
Modified loans, balance	$ 82,000,000
Non purchased loans and leases | Nonaccruing Loans
Loans and Allowance for Loan Losses (Additional Textual) [Abstract]
Outstanding balance of restructured loans		$ 164,000
Non purchased loans and leases | Restructured loans
Loans and Allowance for Loan Losses (Additional Textual) [Abstract]
Outstanding balance of restructured loans	5,965,000	2,596,000
Allowance for loan losses attributable to restructured loans	$ 328,000	$ 193,000