Stockholders' Equity - Regulatory Capital Requirements (Details) - USD ($) $ in Thousands		Dec. 31, 2018		Dec. 31, 2017	Jan. 31, 2016
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital Conservation Buffer on Regulatory Risk-Based Requirements, Phase-in		1.875%		1.25%	0.625%
Total Capital, Actual, Amount		$ 297,402		$ 270,826
Total Capital (to risk weighted assets), Actual, Ratio		11.77%		11.21%
Total Capital, Minimum Capital for Capital Adequacy Purposes, Amount		$ 202,172		$ 193,327
Total Capital (to risk weighted assets), Minimum Capital for Capital Adequacy Purposes, Ratio		8.00%	[1]	8.00%
Tier 1 Risk Based Capital, Actual, Amount		$ 250,925		$ 225,738
Tier 1 Risk Based Capital (to risk weighted assets), Actual, Ratio		9.93%		9.34%
Tier 1 Risk Based Capital, Minimum Capital for Capital Adequacy Purposes, Amount		$ 151,629		$ 144,995
Tier 1 Risk Based Capital (to risk weighted assets), Minimum Capital for Capital Adequacy Purposes, Ratio		6.00%	[1]	6.00%
Tier 1 Leverage Capital, Actual, Amount		$ 250,925		$ 225,738
Tier 1 Leverage Capital (to average assets), Actual, Ratio		8.56%		8.22%
Tier 1 Leverage Capital, Minimum Capital for Capital Adequacy Purposes, Amount		$ 117,198		$ 109,838
Tier 1 Leverage Capital (to average assets), Minimum Capital for Capital Adequacy Purposes, Ratio		4.00%	[1]	4.00%
Common Equity Tier 1 Risk Based Capital, Actual, Amount		$ 250,925		$ 225,738
Common Equity Tier 1 Risk Based Capital (to risk weighted assets), Actual, Ratio		9.93%		9.34%
Common Equity Tier 1 Risk Based Capital, Minimum Capital for Capital Adequacy Purposes, Amount		$ 113,722		$ 108,747
Common Equity Tier 1 Risk Based Capital (to risk weighted assets), Minimum Capital for Capital Adequacy Purposes, Ratio		4.50%	[1]	4.50%
The Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital, Actual, Amount		$ 297,162		$ 270,150
Total Capital (to risk weighted assets), Actual, Ratio		11.76%		11.18%
Total Capital, Minimum Capital for Capital Adequacy Purposes, Amount		$ 202,172		$ 193,301
Total Capital (to risk weighted assets), Minimum Capital for Capital Adequacy Purposes, Ratio		8.00%	[1]	8.00%
Total Capital, Minimum Capital To Be Well Capitalized, Amount		$ 252,715		$ 241,626
Total Capital (to risk weighted assets), Minimum Capital To Be Well Capitalized, Ratio	[2]	10.00%		10.00%
Tier 1 Risk Based Capital, Actual, Amount		$ 265,545		$ 239,910
Tier 1 Risk Based Capital (to risk weighted assets), Actual, Ratio		10.51%		9.93%
Tier 1 Risk Based Capital, Minimum Capital for Capital Adequacy Purposes, Amount		$ 151,629		$ 144,976
Tier 1 Risk Based Capital (to risk weighted assets), Minimum Capital for Capital Adequacy Purposes, Ratio		6.00%	[1]	6.00%
Tier 1 Risk Based Capital, Minimum Capital To Be Well Capitalized, Amount		$ 202,172		$ 193,301
Tier 1 Risk Based Capital (to risk weighted assets), Minimum Capital To Be Well Capitalized, Ratio	[2]	8.00%		8.00%
Tier 1 Leverage Capital, Actual, Amount		$ 265,545		$ 239,910
Tier 1 Leverage Capital (to average assets), Actual, Ratio		9.06%		8.74%
Tier 1 Leverage Capital, Minimum Capital for Capital Adequacy Purposes, Amount		$ 117,198		$ 109,837
Tier 1 Leverage Capital (to average assets), Minimum Capital for Capital Adequacy Purposes, Ratio		4.00%	[1]	4.00%
Tier 1 Leverage Capital, Minimum Capital To Be Well Capitalized, Amount		$ 146,498		$ 137,296
Tier 1 Leverage Capital (to average assets), Minimum Capital To Be Well Capitalized, Ratio	[2]	5.00%		5.00%
Common Equity Tier 1 Risk Based Capital, Actual, Amount		$ 265,545		$ 239,910
Common Equity Tier 1 Risk Based Capital (to risk weighted assets), Actual, Ratio		10.51%		9.93%
Common Equity Tier 1 Risk Based Capital, Minimum Capital for Capital Adequacy Purposes, Amount		$ 113,722		$ 108,732
Common Equity Tier 1 Risk Based Capital (to risk weighted assets), Minimum Capital for Capital Adequacy Purposes, Ratio		4.50%	[1]	4.50%
Common Equity Tier 1 Risk Based Capital, Minimum Capital To Be Well Capitalized, Amount		$ 164,265		$ 157,057
Common Equity Tier 1 Risk Based Capital (to risk weighted assets), Minimum Capital To Be Well Capitalized, Ratio	[2]	6.50%		6.50%

[1] Before application of the capital conservation buffer of 1.875% as of December 31, 2018 and 1.25% as of December 31, 2017, see discussion below.

[2] For the Bank to qualify as "well-capitalized," it must maintain at least the minimum ratios listed. This prompt corrective action framework requirement does not apply to the Company.