Loans and Allowance for Credit Losses - Credit risk profile (Details) - Purchase Credit Impaired $ in Thousands	Jun. 30, 2020 USD ($)
Consumer Loan | Pass
Credit Risk Profile	$ 80,517
Consumer Loan | Watch
Credit Risk Profile	45
Consumer Loan | Special Mention
Credit Risk Profile	25
Consumer Loan | Substandard
Credit Risk Profile	180
Consumer Loan | Doubtful
Credit Risk Profile	0
Consumer Loan | Total by Credit Quality Indicator
Credit Risk Profile	80,767
Commercial Loan | Pass
Credit Risk Profile	457,385
Commercial Loan | Watch
Credit Risk Profile	4,708
Commercial Loan | Special Mention
Credit Risk Profile	0
Commercial Loan | Substandard
Credit Risk Profile	6,355
Commercial Loan | Doubtful
Credit Risk Profile	0
Commercial Loan | Total by Credit Quality Indicator
Credit Risk Profile	468,448
Construction Real Estate | Pass
Credit Risk Profile	103,105
Construction Real Estate | Watch
Credit Risk Profile	4,367
Construction Real Estate | Special Mention
Credit Risk Profile	0
Construction Real Estate | Substandard
Credit Risk Profile	0
Construction Real Estate | Doubtful
Credit Risk Profile	0
Construction Real Estate | Total by Credit Quality Indicator
Credit Risk Profile	107,472
Residential real estate loans | Pass
Credit Risk Profile	620,004
Residential real estate loans | Watch
Credit Risk Profile	1,900
Residential real estate loans | Special Mention
Credit Risk Profile	0
Residential real estate loans | Substandard
Credit Risk Profile	5,453
Residential real estate loans | Doubtful
Credit Risk Profile	0
Residential real estate loans | Total by Credit Quality Indicator
Credit Risk Profile	627,357
Commercial Real Estate | Pass
Credit Risk Profile	829,276
Commercial Real Estate | Watch
Credit Risk Profile	45,262
Commercial Real Estate | Special Mention
Credit Risk Profile	403
Commercial Real Estate | Substandard
Credit Risk Profile	11,590
Commercial Real Estate | Doubtful
Credit Risk Profile	888
Commercial Real Estate | Total by Credit Quality Indicator
Credit Risk Profile	$ 887,419