Stockholders' Equity - Required Capital Amounts and Company's Respective Ratios (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital Required To Be Well Capitalized To Risk Weighted Assets Ratio	10.00%
Common Equity Tier 1 Risk Based Capital Required To Be well Capitalized Amount	6.50%
Tier 1 Risk Based Capital Required To Be Well Capitalized To Risk Weighted Assets Ratio	8.00%
Tier 1 Capital Required To Be Well Capitalized To Average assets Ratio	5.00%
Parent Company [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital Amount	631,573
Total Capital To Risk Weighted Assets Actual Ratio	15.32%
Capital Required For Capital Adequacy Amount	329,818
Capital Required For Capital Adequacy to Risk Weighted Assets Ratio	8.00%
Common Equity Tier 1 Risk Based Capital Amount	570,847
Common Equity Tier 1 Risk Based Capital To Risk Weighted Assets Ratio	13.85%
Common Equity Tier 1 Risk Based Capital Required For Capital Adequacy Amount	185,523
Common Equity Tier 1 Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets Ratio	4.50%
Tier 1 Risk Based Capital Amount	590,016
Tier 1 Risk Based Capital To Risk Weighted Assets Ratio	14.31%
Tier 1 Risk Based Capital Required For Capital Adequacy Amount	247,363
Tier 1 Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets Ratio	6.00%
Tier 1 Capital Amount	590,016
Tier 1 Capital To Average Assets Ratio	9.06%
Tier 1 Capital Required For Capital Adequacy Amount	262,805
Tier 1 Capital Required For Capital Adequacy To Average Assets Ratio	4.00%
BancFirst [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital Amount	584,181
Total Capital To Risk Weighted Assets Actual Ratio	14.19%
Capital Required For Capital Adequacy Amount	329,314
Capital Required For Capital Adequacy to Risk Weighted Assets Ratio	8.00%
Capital Required To Be Well Capitalized Amount	411,643
Capital Required To Be Well Capitalized To Risk Weighted Assets Ratio	10.00%
Common Equity Tier 1 Risk Based Capital Amount	527,295
Common Equity Tier 1 Risk Based Capital To Risk Weighted Assets Ratio	12.81%
Common Equity Tier 1 Risk Based Capital Required For Capital Adequacy Amount	185,239
Common Equity Tier 1 Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets Ratio	4.50%
Common Equity Tier 1 Risk Based Capital Required To Be well Capitalized Amount	267,568
Common Equity Tier 1 Risk Based Capital Required To Be well Capitalized Amount	6.50%
Tier 1 Risk Based Capital Amount	542,624
Tier 1 Risk Based Capital To Risk Weighted Assets Ratio	13.18%
Tier 1 Risk Based Capital Required For Capital Adequacy Amount	246,986
Tier 1 Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets Ratio	6.00%
Tier 1 Risk Based Capital Required To Be well Capitalized Amount	329,314
Tier 1 Risk Based Capital Required To Be Well Capitalized To Risk Weighted Assets Ratio	8.00%
Tier 1 Capital Amount	542,624
Tier 1 Capital To Average Assets Ratio	8.34%
Tier 1 Capital Required For Capital Adequacy Amount	262,065
Tier 1 Capital Required For Capital Adequacy To Average Assets Ratio	4.00%
Tier 1 Capital Required To Be Well Capitalized Amount	327,581
Tier 1 Capital Required To Be Well Capitalized To Average assets Ratio	5.00%

Common equity tier one risk based capital.

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Common Equity Tier One Risk Based Capital Required To Be Well Capitalized.

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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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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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Tier 1 Risk Based Capital as defined in the regulations.

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

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