Non Purchased Loans - Narrative (Details)	3 Months Ended	9 Months Ended
	Sep. 30, 2019 USD ($) loan	Sep. 30, 2019 USD ($) loan	Sep. 30, 2018 USD ($) loan	Dec. 31, 2018 USD ($)
Loans and Allowance for Loan Losses (Additional Textual) [Abstract]
Allowance for loan losses attributable to restructured loans	$ 50,814,000	$ 50,814,000		$ 49,026,000
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
Threshold for impairment measurement	$ 500,000	$ 500,000
Number of Loans | loan	1	6	5
Troubled debt restructured		$ 61,000	$ 0
Nonperforming loans charged-off past due period		90 days
Number of restructured loans | loan		1	2
Restructured loans discontinued past due period		90 days	90 days
Remaining availability under commitments to lend additional funds on restructured loans	$ 1,000	$ 1,000	$ 19,000
Non purchased loans and leases | Nonaccruing Loans
Loans and Allowance for Loan Losses (Additional Textual) [Abstract]
Outstanding balance of restructured loans	40,000	40,000	228,000
Non purchased loans and leases | Restructured Loans
Loans and Allowance for Loan Losses (Additional Textual) [Abstract]
Outstanding balance of restructured loans	3,101,000	3,101,000	3,147,000
Allowance for loan losses attributable to restructured loans	$ 30,000	$ 30,000	$ 33,000