Loans and Allowance for Loan Losses - Allowance for credit losses (Details)	12 Months Ended
	Dec. 31, 2018 USD ($) contract borrower loan	Dec. 31, 2017 USD ($) contract loan
Schedule of Available-for-sale Securities [Line Items]
Amount of interest that would have been accrued from non performing financial receivable, totaled	$ 200,000	$ 200,000
Amount of recorded investment in new troubled debt restructurings, totaled	$ 248,000	$ 263,000
Number of new loans modified as TDRs | loan	0	0
Number of TDRs accounts | contract	2	2
Non-performing TDRs
Schedule of Available-for-sale Securities [Line Items]
Amount of recorded investment in new troubled debt restructurings, totaled	$ 43,521,000	$ 46,162,000
Number of TDRs accounts | contract	1	1
Performing
Schedule of Available-for-sale Securities [Line Items]
Amount of recorded investment in new troubled debt restructurings, totaled	$ 204,500,000	$ 216,500,000
Number of TDRs accounts | contract	1	1
Consumer
Schedule of Available-for-sale Securities [Line Items]
Amount of consumer and indirect loans, outstanding	$ 89,340
Amount of consumer and indirect loans, specific reserves	$ 21,789
Number of loan consumer and indirect loans | contract	2
Amount of recorded investment in new troubled debt restructurings, totaled	$ 44,000	$ 46,000
Number of TDRs accounts | contract	1	1
Number of borrowers | borrower	2