Regulatory Capital Requirements (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier One Capital Required for Capital Adequacy	$ 197,189	$ 154,522
Common Equity Tier One Capital Required for Capital Adequacy to Average Assets	4.50%	4.50%
Common Equity Tier One Capital	$ 510,618	$ 386,689
Common Equity Tier One Capital to Average Assets	11.70%	11.30%
Tier One Leverage Capital Required for Capital Adequacy	$ 201,920	$ 159,494
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%	4.00%
Tier One Leverage Capital	$ 530,920	$ 406,687
Tier One Leverage Capital to Average Assets	10.50%	10.20%
Tier One Risk Based Capital Required for Capital Adequacy	$ 262,918	$ 206,029
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	6.00%	6.00%
Tier One Risk Based Capital	$ 530,920	$ 406,687
Tier One Risk Based Capital to Risk Weighted Assets	12.10%	11.80%
Capital Required for Capital Adequacy	$ 350,558	$ 274,706
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%	8.00%
Capital	$ 566,268	$ 439,044
Capital to Risk Weighted Assets	12.90%	12.80%
Capital conservation buffer, percentage	4.92%
Heritage Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Common Equity Tier One Capital Required for Capital Adequacy	$ 197,004	$ 154,400
Common Equity Tier One Capital Required for Capital Adequacy to Average Assets	4.50%	4.50%
Common Equity Tier One Capital Required to be Well-Capitalized	$ 284,561	$ 223,023
Common Equity Tier One Capital Required to be Well Capitalized to Average Assets	6.50%	6.50%
Common Equity Tier One Capital	$ 513,993	$ 391,092
Common Equity Tier One Capital to Average Assets	11.70%	11.40%
Tier One Leverage Capital Required for Capital Adequacy	$ 203,339	$ 159,300
Tier One Leverage Capital Required for Capital Adequacy to Average Assets	4.00%	4.00%
Tier One Leverage Capital Required to be Well Capitalized	$ 254,174	$ 199,125
Tier One Leverage Capital Required to be Well Capitalized to Average Assets	5.00%	5.00%
Tier One Leverage Capital	$ 513,993	$ 391,092
Tier One Leverage Capital to Average Assets	10.10%	9.80%
Tier One Risk Based Capital Required for Capital Adequacy	$ 262,671	$ 205,867
Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	6.00%	6.00%
Tier One Risk Based Capital Required to be Well Capitalized	$ 350,229	$ 274,490
Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets	8.00%	8.00%
Tier One Risk Based Capital	$ 513,993	$ 391,092
Tier One Risk Based Capital to Risk Weighted Assets	11.70%	11.40%
Capital Required for Capital Adequacy	$ 350,229	$ 274,490
Capital Required for Capital Adequacy to Risk Weighted Assets	8.00%	8.00%
Capital Required to be Well Capitalized	$ 437,786	$ 343,112
Capital Required to be Well Capitalized to Risk Weighted Assets	10.00%	10.00%
Capital	$ 549,341	$ 423,348
Capital to Risk Weighted Assets	12.50%	12.30%
Capital conservation buffer, percentage	4.55%

Capital Conservation Buffer, Percentage

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Common Equity Tier One Capital to Average Assets

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The amount of total capital as defined in the regulations.

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The minimum Total risk based capital ratio (total capital divided by risk weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The amount of Total Capital required to be categorized as well as capitalized under the regulatory framework for prompt corrective action.

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The Total risk based capital ratio (total capital divided by risk weighted assets) required to be categorized as "well capitalized", in the regulatory framework for prompt corrective action.

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Total Capital divided by risk weighted assets as defined in the regulations.

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Amount of Common Equity Tier One Risk-based Capital, as defined by regulatory framework.

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Amount of Common Equity Tier 1 Risk-based Capital required to be categorized as adequately capitalized under regulatory framework for prompt corrective action.

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Amount of Common Equity Tier 1 Risk-based Capital required to be categorized as well-capitalized under regulatory framework for prompt corrective action.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Tier 1 Leverage Capital as defined in the regulations. Also called Core Capital.

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The minimum amount of Tier 1 Leverage Capital required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The minimum amount of Tier 1 Leverage Capital for capital adequacy purposes divided by average assets as defined in the regulations.

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The amount of Tier 1 Leverage Capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action.

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Tier 1 Leverage Capital divided by average assets as defined in the regulations.

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Tier 1 Risk Based Capital as defined in the regulations.

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The minimum amount of Tier 1 Risk Based Capital required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The minimum Tier One Capital Ratio (Tier one capital divided by risk-weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

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The amount of Tier 1 Risk Based Capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action.

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Tier 1 capital divided by risk weighted assets as defined by regulations.

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