Regulatory Matters - Compliance with Regulatory Capital Requirements under Banking Regulations (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Sierra Bancorp And Subsidiary [Member]
Leverage Ratio
Sierra Bancorp and subsidiary	$ 306,744	$ 282,484
Minimum requirement for "Well-Capitalized" institutions	128,769	122,962
Minimum regulatory requirement	$ 103,016	$ 98,370
Bank of the Sierra	11.91%	11.49%
Minimum requirement for "Well-Capitalized" institutions	5.00%	5.00%
Minimum regulatory requirement	4.00%	4.00%
Common Equity Tier 1 Capital Ratio
Sierra Bancorp and subsidiary	$ 271,799	$ 247,717
Minimum requirements for "Well-Capitalized" institutions	133,095	127,709
Minimum regulatory requirement	$ 92,143	$ 88,414
Bank of the Sierra	13.27%	12.61%
Minimum requirements for "Well-Capitalized" institutions	6.50%	6.50%
Minimum regulatory requirement	4.50%	4.50%
Tier 1 Risk-Based Capital Ratio
Sierra Bancorp and subsidiary	$ 306,744	$ 282,484
Minimum requirement for "Well-Capitalized" institutions	163,809	157,181
Minimum regulatory requirement	$ 122,857	$ 117,885
Bank of the Sierra	14.98%	14.38%
Minimum requirement for "Well-Capitalized" institutions	8.00%	8.00%
Minimum regulatory requirement	6.00%	6.00%
Total Risk-Based Capital Ratio
Capital	$ 316,981	$ 292,618
Minimum requirement for "Well-Capitalized" institutions	204,762	196,476
Minimum regulatory requirement	$ 163,809	$ 157,181
Bank of the Sierra	15.48%	14.89%
Minimum requirement for "Well-Capitalized" institutions	10.00%	10.00%
Minimum regulatory requirement	8.00%	8.00%
Bank Of Sierra [Member]
Leverage Ratio
Sierra Bancorp and subsidiary	$ 301,963	$ 280,184
Minimum requirement for "Well-Capitalized" institutions	128,753	140,092
Minimum regulatory requirement	$ 103,002	$ 98,364
Bank of the Sierra	11.73%	11.39%
Minimum requirement for "Well-Capitalized" institutions	5.00%	5.00%
Minimum regulatory requirement	4.00%	4.00%
Common Equity Tier 1 Capital Ratio
Sierra Bancorp and subsidiary	$ 301,963	$ 280,184
Minimum requirements for "Well-Capitalized" institutions	133,077	127,776
Minimum regulatory requirement	$ 92,130	$ 88,461
Bank of the Sierra	14.75%	14.25%
Minimum requirements for "Well-Capitalized" institutions	6.50%	6.50%
Minimum regulatory requirement	4.50%	4.50%
Tier 1 Risk-Based Capital Ratio
Sierra Bancorp and subsidiary	$ 301,963	$ 280,184
Minimum requirement for "Well-Capitalized" institutions	163,787	157,263
Minimum regulatory requirement	$ 122,840	$ 117,947
Bank of the Sierra	14.75%	14.25%
Minimum requirement for "Well-Capitalized" institutions	8.00%	8.00%
Minimum regulatory requirement	6.00%	6.00%
Total Risk-Based Capital Ratio
Capital	$ 312,200	$ 290,318
Minimum requirement for "Well-Capitalized" institutions	204,734	196,579
Minimum regulatory requirement	$ 163,787	$ 157,263
Bank of the Sierra	15.25%	14.77%
Minimum requirement for "Well-Capitalized" institutions	10.00%	10.00%
Minimum regulatory requirement	8.00%	8.00%

Common Equity Tier 1 (CET1) Risk Based Capital as defined in the regulations.

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The minimum Common Equity Tier 1 (CET1) Capital Ratio (CET 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 Common Equity Tier 1 (CET1) Risk Based Capital required to be categorized as well capitalized under the regulatory framework for prompt corrective action.

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The Common Equity Tier 1 (CET1) capital ratio (CET 1 capital divided by risk weighted assets) required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action.

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Common Equity Tier 1 (CET1) capital divided by risk weighted assets as defined by regulations.

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Common equity tier 1 capital ratio.

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The amount of total capital as defined in the regulations.

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

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

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