Regulatory Capital - Summary of Regulatory Capital Requirement (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total capital (to risk-weighted assets), Actual, Amount	$ 640,728	$ 548,364
Total capital (to risk-weighted assets), Actual, Ratio	14.38%	13.95%
Total capital (to risk-weighted assets), For capital adequacy purposes, Amount	$ 356,455	$ 314,395
Total capital (to risk-weighted assets), For capital adequacy purposes, Ratio	8.00%	8.00%
Total capital (to risk-weighted assets), Required for capital1 adequacy purposes with capital buffer, Amount	$ 467,847	$ 412,644
Total capital (to risk-weighted assets), Required for capital1 adequacy purposes with capital buffer, Ratio	10.50%	10.50%
Tier 1 capital (to average assets), Actual, Amount	$ 601,331	$ 530,643
Tier 1 capital (to average assets), Actual, Ratio	13.49%	13.50%
Tier 1 capital (to average assets), For capital adequacy purposes, Amount	$ 267,456	$ 235,796
Tier 1 capital (to average assets), For capital adequacy purpose, Ratio	6.00%	6.00%
Tier 1 capital (to average assets), Required for capital1 adequacy purposes with capital buffer, Amount	$ 378,896	$ 334,044
Tier 1 capital (to average assets), Required for capital1 adequacy purposes with capital buffer, Ratio	8.50%	8.50%
Common equity tier 1 capital, Actual Amount	$ 485,235	$ 473,150
Common equity tier 1 capital, Actual Ratio	10.89%	12.04%
Common equity tier 1 capital, For capital adequacy purposes, Amount	$ 200,510	$ 176,846
Common equity tier 1 capital, For capital adequacy purpose, Ratio	4.50%	4.50%
Common equity tier 1 capital (to risk-weighted assets), Required for capital adequacy purposes with capital buffer, Amount	$ 311,905	$ 275,094
Common equity tier 1 capital (to risk-weighted assets), Required for capital adequacy purposes with capital buffer, Ratio	7.00%	7.00%
Tier 1 capital (to average assets), Actual, Amount	$ 601,331	$ 530,643
Tier 1 capital (to average assets), Actual, Ratio	10.82%	10.50%
Tier 1 capital (to average assets), For capital adequacy purposes, Amount	$ 222,304	$ 202,111
Tier 1 capital (to average assets), For capital adequacy purpose, Ratio	4.00%	4.00%
Tier 1 capital (to average assets), Required for capital1 adequacy purposes with capital buffer, Amount	$ 222,304	$ 202,111
Tier 1 capital (to average assets), Required for capital1 adequacy purposes with capital buffer, Ratio	4.00%	4.00%
Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total capital (to risk-weighted assets), Actual, Amount	$ 514,974	$ 497,227
Total capital (to risk-weighted assets), Actual, Ratio	11.56%	12.65%
Total capital (to risk-weighted assets), For capital adequacy purposes, Amount	$ 356,383	$ 314,452
Total capital (to risk-weighted assets), For capital adequacy purposes, Ratio	8.00%	8.00%
Total capital (to risk-weighted assets), Required for capital1 adequacy purposes with capital buffer, Amount	$ 467,753	$ 412,718
Total capital (to risk-weighted assets), Required for capital1 adequacy purposes with capital buffer, Ratio	10.50%	10.50%
Total capital (to risk-weighted assets), For well capitalized purpose, Amount	$ 445,479	$ 393,065
Total capital (to risk-weighted assets), For well capitalized purpose, Ratio	10.00%	10.00%
Tier 1 capital (to average assets), Actual, Amount	$ 475,588	$ 479,506
Tier 1 capital (to average assets), Actual, Ratio	10.67%	12.20%
Tier 1 capital (to average assets), For capital adequacy purposes, Amount	$ 267,435	$ 235,823
Tier 1 capital (to average assets), For capital adequacy purpose, Ratio	6.00%	6.00%
Tier 1 capital (to average assets), Required for capital1 adequacy purposes with capital buffer, Amount	$ 378,866	$ 334,082
Tier 1 capital (to average assets), Required for capital1 adequacy purposes with capital buffer, Ratio	8.50%	8.50%
Tier 1 capital (to average assets), For well capitalized purpose, Amount	$ 356,580	$ 314,430
Tier 1 capital (to average assets), For well capitalized purposes, Ratio	8.00%	8.00%
Common equity tier 1 capital, Actual Amount	$ 475,588	$ 479,506
Common equity tier 1 capital, Actual Ratio	10.67%	12.20%
Common equity tier 1 capital, For capital adequacy purposes, Amount	$ 200,576	$ 176,867
Common equity tier 1 capital, For capital adequacy purpose, Ratio	4.50%	4.50%
Common equity tier 1 capital (to risk-weighted assets), Required for capital adequacy purposes with capital buffer, Amount	$ 312,007	$ 275,126
Common equity tier 1 capital (to risk-weighted assets), Required for capital adequacy purposes with capital buffer, Ratio	7.00%	7.00%
Common equity tier 1 capital, For well capitalized purpose, Amount	$ 289,721	$ 255,475
Common equity tier 1 capital, For well capitalized purposes, Ratio	6.50%	6.50%
Tier 1 capital (to average assets), Actual, Amount	$ 475,588	$ 479,506
Tier 1 capital (to average assets), Actual, Ratio	8.57%	9.49%
Tier 1 capital (to average assets), For capital adequacy purposes, Amount	$ 221,978	$ 202,110
Tier 1 capital (to average assets), For capital adequacy purpose, Ratio	4.00%	4.00%
Tier 1 capital (to average assets), Required for capital1 adequacy purposes with capital buffer, Amount	$ 221,978	$ 202,110
Tier 1 capital (to average assets), Required for capital1 adequacy purposes with capital buffer, Ratio	4.00%	4.00%
Tier 1 capital (to average assets), For well capitalized purpose, Amount	$ 277,473	$ 252,638
Tier 1 capital (to average assets), For well capitalized purposes, Ratio	5.00%	5.00%