Quantitative Information about Level 3 Fair Value Measurements (Details) - Non-Recurring Measurements - USD ($) $ in Thousands		9 Months Ended	12 Months Ended
		Sep. 30, 2017	Dec. 31, 2016
Quantitative Information About Level 3 Fair Value Measurements
Fair Value		$ 8,058	$ 13,503
Level 3
Quantitative Information About Level 3 Fair Value Measurements
Fair Value		8,058	13,503
Other real estate owned | Level 3
Quantitative Information About Level 3 Fair Value Measurements
Fair Value			7,839
Other real estate owned | Sales Comparison Approach | Level 3
Quantitative Information About Level 3 Fair Value Measurements
Fair Value		$ 1,616	7,767
Other real estate owned | Combined Approach | Level 3
Quantitative Information About Level 3 Fair Value Measurements
Fair Value			$ 72
Other real estate owned | Minimum Range | Sales Comparison Approach | Level 3
Unobservable Inputs
Selling Costs	[1]	8.00%	6.00%
Adjustment to Comparables	[1]		0.00%
Other real estate owned | Minimum Range | Combined Approach | Level 3
Unobservable Inputs
Selling Costs	[1]		10.00%
Adjustment to Comparables	[1]		10.00%
Other real estate owned | Maximum Range | Sales Comparison Approach | Level 3
Unobservable Inputs
Selling Costs	[1]	10.00%	10.00%
Adjustment to Comparables	[1]		10.00%
Other real estate owned | Maximum Range | Combined Approach | Level 3
Unobservable Inputs
Selling Costs	[1]		10.00%
Adjustment to Comparables	[1]		10.00%
Other real estate owned | Weighted Average Range | Sales Comparison Approach | Level 3
Unobservable Inputs
Selling Costs	[1]	9.30%	6.90%
Adjustment to Comparables	[1]		0.10%
Other real estate owned | Weighted Average Range | Combined Approach | Level 3
Unobservable Inputs
Selling Costs	[1]		10.00%
Adjustment to Comparables	[1]		10.00%
Collateral-dependent Impaired Loans, Net of ALLL | Level 3
Quantitative Information About Level 3 Fair Value Measurements
Fair Value		$ 6,442	$ 5,664
Collateral-dependent Impaired Loans, Net of ALLL | Sales Comparison Approach | Level 3
Quantitative Information About Level 3 Fair Value Measurements
Fair Value		3,020	1,982
Collateral-dependent Impaired Loans, Net of ALLL | Cost Approach | Level 3
Quantitative Information About Level 3 Fair Value Measurements
Fair Value		17	110
Collateral-dependent Impaired Loans, Net of ALLL | Combined Approach | Level 3
Quantitative Information About Level 3 Fair Value Measurements
Fair Value		$ 3,405	$ 3,572
Collateral-dependent Impaired Loans, Net of ALLL | Minimum Range | Sales Comparison Approach | Level 3
Unobservable Inputs
Selling Costs	[1]	6.00%	8.00%
Collateral-dependent Impaired Loans, Net of ALLL | Minimum Range | Cost Approach | Level 3
Unobservable Inputs
Selling Costs	[1]	20.00%	6.00%
Collateral-dependent Impaired Loans, Net of ALLL | Minimum Range | Combined Approach | Level 3
Unobservable Inputs
Selling Costs	[1]	10.00%	10.00%
Adjustment to Comparables	[1]	20.00%	20.00%
Collateral-dependent Impaired Loans, Net of ALLL | Maximum Range | Sales Comparison Approach | Level 3
Unobservable Inputs
Selling Costs	[1]	10.00%	10.00%
Collateral-dependent Impaired Loans, Net of ALLL | Maximum Range | Cost Approach | Level 3
Unobservable Inputs
Selling Costs	[1]	20.00%	20.00%
Collateral-dependent Impaired Loans, Net of ALLL | Maximum Range | Combined Approach | Level 3
Unobservable Inputs
Selling Costs	[1]	10.00%	10.00%
Adjustment to Comparables	[1]	20.00%	20.00%
Collateral-dependent Impaired Loans, Net of ALLL | Weighted Average Range | Sales Comparison Approach | Level 3
Unobservable Inputs
Selling Costs	[1]	9.20%	9.60%
Collateral-dependent Impaired Loans, Net of ALLL | Weighted Average Range | Cost Approach | Level 3
Unobservable Inputs
Selling Costs	[1]	20.00%	6.60%
Collateral-dependent Impaired Loans, Net of ALLL | Weighted Average Range | Combined Approach | Level 3
Unobservable Inputs
Selling Costs	[1]	10.00%	10.00%
Adjustment to Comparables	[1]	20.00%	20.00%

[1] The range for selling costs and adjustments to comparables indicate reductions to the fair value.