Regulatory Matters (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Company
Total Capital
Total Capital (to risk-weighted assets), Actual, Capital Amount	$ 396,736	$ 355,722
Total Capital (to risk weighted assets), Actual, Ratio (as a percent)	12.60%	13.70%
Total Capital, Minimum Amount Required for Adequately Capitalized, Capital Amount	$ 251,761	$ 207,657
Total Capital (to risk weighted assets), Minimum Amount Required for Adequately Capitalized, Ratio (as a percent)	8.00%	8.00%
Tier I Capital
Tier I Capital, (to risk-weighted assets), Actual, Capital Amount	$ 385,492	$ 347,411
Tier I Capital (to risk weighted assets), Actual, Ratio (as a percent)	12.20%	13.40%
Tier I Capital, Minimum Amount Required for Adequately Capitalized, Capital Amount	$ 188,821	$ 155,743
Tier I Capital (to risk weighted assets), Minimum Amount Required for Adequately Capitalized, Ratio (as a percent)	6.00%	6.00%
Common Equity Tier I Capital 1
Common Equity Tier I Capital 1, Actual, Capital Amount	$ 343,911	$ 305,830
Common Equity Tier I Capital 1 (to risk weighted assets), Ratio (as a percent)	10.90%	11.80%
Common Equity Tier I Capital 1, Minimum Amount Required for Adequately Capitalized, Capital Amount	$ 141,616	$ 116,807
Common Equity Tier I Capital 1 (to risk weighted assets, Minimum Amount Required for Adequately Capitalized, Ratio (as a percent)	4.50%	4.50%
Common Equity Tier I Capital 1
Common Equity Tier I Capital 1, Actual, Capital Amount	$ 385,492	$ 347,411
Common Equity Tier I Capital 1 (to risk weighted assets), Ratio (as a percent)	10.10%	10.90%
Common Equity Tier I Capital 1, Minimum Amount Required for Adequately Capitalized, Capital Amount	$ 152,110	$ 127,318
Common Equity Tier I Capital 1, Minimum Amount Required for Adequately Capitalized, Capital Amount (as a percent)	4.00%	4.00%
Federal Deposit Corporation And Federal Reserve Board | Rules Effective January 1, 2015
Tier 1 Leverage
Deductions and other adjustments to CET1 beginning (as a percent)	40.00%
Additional deductions and other adjustments to CET1 subsequent years (as a percent)	20.00%
Basel III Capital Rules related to CET1, period (in years)	4 years
Federal Deposit Corporation And Federal Reserve Board | Rules Phased in beginning January 2016
Tier 1 Leverage
New capital conservation buffer requirement beginning Ratio	0.625%
Basel III Capital Rules related to CET1, period (in years)	4 years
Additional capital conservation buffer requirement subsequent years Ratio	2.50%
Bank
Total Capital
Total Capital (to risk-weighted assets), Actual, Capital Amount	$ 461,120	$ 406,638
Total Capital (to risk weighted assets), Actual, Ratio (as a percent)	14.80%	15.70%
Total Capital, Minimum Amount Required for Adequately Capitalized, Capital Amount	$ 248,823	$ 207,567
Total Capital (to risk weighted assets), Minimum Amount Required for Adequately Capitalized, Ratio (as a percent)	8.00%	8.00%
Total capital, Minimum Amount To Be Well Capitalized, Capital Amount	$ 311,029	$ 259,459
Total Capital (to risk weighted assets), Minimum Amount To Be Well Capitalized, Ratio (as a percent)	10.00%	10.00%
Tier I Capital
Tier I Capital, (to risk-weighted assets), Actual, Capital Amount	$ 449,982	$ 398,327
Tier I Capital (to risk weighted assets), Actual, Ratio (as a percent)	14.50%	15.40%
Tier I Capital, Minimum Amount Required for Adequately Capitalized, Capital Amount	$ 186,617	$ 155,675
Tier I Capital (to risk weighted assets), Minimum Amount Required for Adequately Capitalized, Ratio (as a percent)	6.00%	6.00%
Tier I Capital, Minimum Amount To Be Well Capitalized, Capital Amount	$ 248,823	$ 207,567
Tier I Capital (to risk weighted assets), Minimum Amount To Be Well Capitalized, Ratio (as a percent)	8.00%	8.00%
Common Equity Tier I Capital 1
Common Equity Tier I Capital 1, Actual, Capital Amount	$ 449,982	$ 398,327
Common Equity Tier I Capital 1 (to risk weighted assets), Ratio (as a percent)	14.50%	15.40%
Common Equity Tier I Capital 1, Minimum Amount Required for Adequately Capitalized, Capital Amount	$ 139,963	$ 116,756
Common Equity Tier I Capital 1 (to risk weighted assets, Minimum Amount Required for Adequately Capitalized, Ratio (as a percent)	4.50%	4.50%
Common Equity Tier I Capital 1, Minimum Amount To Be Well Capitalized, Capital Amount	$ 202,169	$ 168,648
Common Equity Tier I Capital 1 (to risk weighted assets), Minimum Amount To Be Well Capitalized, Ratio (as a percent)	6.50%	6.50%
Common Equity Tier I Capital 1
Common Equity Tier I Capital 1, Actual, Capital Amount	$ 449,982	$ 398,327
Common Equity Tier I Capital 1 (to risk weighted assets), Ratio (as a percent)	12.00%	12.50%
Common Equity Tier I Capital 1, Minimum Amount Required for Adequately Capitalized, Capital Amount	$ 150,515	$ 127,593
Common Equity Tier I Capital 1, Minimum Amount Required for Adequately Capitalized, Capital Amount (as a percent)	4.00%	4.00%
Common Equity Tier I Capital 1, Minimum Amount To Be Well Capitalized, Capital Amount	$ 188,144	$ 159,491
Common Equity Tier I Capital 1, Minimum Amount To Be Well Capitalized, Capital Amount (as a percent)	5.00%	5.00%
Joy State Bank
Total Capital
Total Capital (to risk-weighted assets), Actual, Capital Amount	$ 4,474
Total Capital (to risk weighted assets), Actual, Ratio (as a percent)	12.40%
Total Capital, Minimum Amount Required for Adequately Capitalized, Capital Amount	$ 2,876
Total Capital (to risk weighted assets), Minimum Amount Required for Adequately Capitalized, Ratio (as a percent)	8.00%
Total capital, Minimum Amount To Be Well Capitalized, Capital Amount	$ 3,595
Total Capital (to risk weighted assets), Minimum Amount To Be Well Capitalized, Ratio (as a percent)	10.00%
Tier I Capital
Tier I Capital, (to risk-weighted assets), Actual, Capital Amount	$ 4,368
Tier I Capital (to risk weighted assets), Actual, Ratio (as a percent)	12.20%
Tier I Capital, Minimum Amount Required for Adequately Capitalized, Capital Amount	$ 2,157
Tier I Capital (to risk weighted assets), Minimum Amount Required for Adequately Capitalized, Ratio (as a percent)	6.00%
Tier I Capital, Minimum Amount To Be Well Capitalized, Capital Amount	$ 2,876
Tier I Capital (to risk weighted assets), Minimum Amount To Be Well Capitalized, Ratio (as a percent)	8.00%
Common Equity Tier I Capital 1
Common Equity Tier I Capital 1, Actual, Capital Amount	$ 4,368
Common Equity Tier I Capital 1 (to risk weighted assets), Ratio (as a percent)	12.20%
Common Equity Tier I Capital 1, Minimum Amount Required for Adequately Capitalized, Capital Amount	$ 1,618
Common Equity Tier I Capital 1 (to risk weighted assets, Minimum Amount Required for Adequately Capitalized, Ratio (as a percent)	4.50%
Common Equity Tier I Capital 1, Minimum Amount To Be Well Capitalized, Capital Amount	$ 2,336
Common Equity Tier I Capital 1 (to risk weighted assets), Minimum Amount To Be Well Capitalized, Ratio (as a percent)	6.50%
Common Equity Tier I Capital 1
Common Equity Tier I Capital 1, Actual, Capital Amount	$ 4,368
Common Equity Tier I Capital 1 (to risk weighted assets), Ratio (as a percent)	9.30%
Common Equity Tier I Capital 1, Minimum Amount Required for Adequately Capitalized, Capital Amount	$ 1,878
Common Equity Tier I Capital 1, Minimum Amount Required for Adequately Capitalized, Capital Amount (as a percent)	4.00%
Common Equity Tier I Capital 1, Minimum Amount To Be Well Capitalized, Capital Amount	$ 2,348
Common Equity Tier I Capital 1, Minimum Amount To Be Well Capitalized, Capital Amount (as a percent)	5.00%