Stockholders' Equity - Required Capital Amounts and Company's Respective Ratios (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Tier 1 Risk Based Capital Required To Be Well Capitalized To Risk Weighted Assets Ratio	6.00%
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 To Risk Weighted Assets Actual Amount	$ 601,492
Total Capital To Risk Weighted Assets Actual Ratio	14.60%
Capital Required For Capital Adequacy Amount	329,665
Capital Required For Capital Adequacy to Risk Weighted Assets Ratio	8.00%
Tier 1 Risk Based Capital Amount	562,025
Tier 1 Risk Based Capital To Risk Weighted Assets Ratio	13.64%
Tier 1 Risk Based Capital Required For Capital Adequacy Amount	164,832
Tier 1 Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets Ratio	4.00%
Tier 1 Capital Amount	562,025
Tier 1 Capital To Average Assets Ratio	8.85%
Tier 1 Capital Required For Capital Adequacy Amount	192,198
Tier 1 Capital Required For Capital Adequacy To Average Assets Ratio	3.00%
BancFirst [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital To Risk Weighted Assets Actual Amount	559,960
Total Capital To Risk Weighted Assets Actual Ratio	13.61%
Capital Required For Capital Adequacy Amount	329,121
Capital Required For Capital Adequacy to Risk Weighted Assets Ratio	8.00%
Capital Required To Be Well Capitalized Amount	411,401
Capital Required To Be Well Capitalized To Risk Weighted Assets Ratio	10.00%
Tier 1 Risk Based Capital Amount	520,493
Tier 1 Risk Based Capital To Risk Weighted Assets Ratio	12.65%
Tier 1 Risk Based Capital Required For Capital Adequacy Amount	164,560
Tier 1 Risk Based Capital Required For Capital Adequacy To Risk Weighted Assets Ratio	4.00%
Tier 1 Risk Based Capital Required To Be well Capitalized Amount	246,841
Tier 1 Risk Based Capital Required To Be Well Capitalized To Risk Weighted Assets Ratio	6.00%
Tier 1 Capital Amount	520,493
Tier 1 Capital To Average Assets Ratio	8.21%
Tier 1 Capital Required For Capital Adequacy Amount	191,602
Tier 1 Capital Required For Capital Adequacy To Average Assets Ratio	3.00%
Tier 1 Capital Required To Be Well Capitalized Amount	$ 319,337
Tier 1 Capital Required To Be Well Capitalized To Average assets Ratio	5.00%