Recent Developments, Including Mergers & Acquisitions	12 Months Ended
Dec. 31, 2011
Recent Developments, Including Mergers & Acquisitions [Abstract]
Recent Developments, Including Mergers & Acquisitions	(2) RECENT DEVELOPMENTS, INCLUDING MERGERS & ACQUISITIONS On July 12, 2011, the Company completed the acquisition of FBC Financial Corporation and its subsidiary bank, 1st Bank Oklahoma with banking locations in Claremore, Verdigris, and Inola, Oklahoma. The Company paid a premium of $1.5 million above the equity capital of FBC Financial Corporation. At acquisition, 1st Bank Oklahoma had approximately $217 million in total assets, $116 million in loans, $178 million in deposits and $18 million in equity capital. 1st Bank Oklahoma operated as a subsidiary of BancFirst Corporation until it was merged into BancFirst on February 17, 2012. The acquisition did not have a material effect on the Company's consolidated financial statements. The Federal Reserve enacted a final rule on June 29, 2011 establishing the debit card interchange rate at $0.21 per transaction and five basis points multiplied by the value of the transaction that was effective on October 1, 2011 for banks exceeding $10 billion in assets. Although the rule does not apply directly to the Company, the possible competitive response may have an impact on the Company's pricing of these services. On December 15, 2010, the Company completed the acquisition of OK Bancorporation, Inc., and its subsidiary bank, The Okemah National Bank. At acquisition, The Okemah National Bank had approximately $73 million in total assets, $32 million in loans, $62 million in deposits, and $9 million in equity capital. The Okemah National Bank operated as a subsidiary of BancFirst Corporation until it was merged into BancFirst on October 21, 2011. The acquisition did not have a material effect on the Company's consolidated financial statements. On December 10, 2010, the Company completed the acquisition of Exchange Bancshares of Moore, Inc., and its subsidiary bank, Exchange National Bank of Moore. At acquisition, Exchange National Bank of Moore had approximately $147 million in total assets, $47 million in loans, $116 million in deposits, and $10 million in equity capital. Exchange National Bank of Moore operated as a subsidiary of BancFirst Corporation until it was merged into BancFirst on June 17, 2011. The acquisition did not have a material effect on the Company's consolidated financial statements. On October 8, 2010, the Company completed the acquisition of Union National Bancshares, Inc., and its subsidiary bank, Union Bank of Chandler with offices in Chandler and Tulsa, Oklahoma. At acquisition, Union Bank of Chandler had approximately $134 million in total assets, $90 million in loans, $117 million in deposits, and $15 million in equity capital. Union Bank of Chandler operated as a subsidiary of BancFirst Corporation until it was merged into BancFirst on November 12, 2010. The acquisition did not have a material effect on the Company's consolidated financial statements. The Company recorded a total of $13.3 million of goodwill and core deposit intangibles as a result of the three acquisitions completed in 2010. The combined acquisitions added approximately $371 million in total assets, $169 million in loans and $295 million in deposits. The effects of these acquisitions were included in the consolidated financial statements of the Company from the date of acquisition forward. The Company does not believe these acquisitions, individually or in aggregate were material to the Company's consolidated financial statements. Effective as of June 30, 2010, the Company ceased participation in the Transaction Account Guarantee Program ("TAGP") for extended coverage of noninterest-bearing transaction deposit accounts. Accordingly, the standard deposit insurance amount was in effect for the Company's deposit accounts through December 31, 2010. In November 2010, the Federal Deposit Insurance Corporation ("FDIC") issued a final rule to implement provisions of the Dodd-Frank Act that provide for temporary unlimited coverage for noninterest-bearing transaction accounts. The separate coverage for noninterest-bearing transaction accounts became effective on December 31, 2010 and terminates on December 31, 2012. On April 1, 2010, the Company's insurance agency BancFirst Insurance Services, Inc., formerly known as Wilcox, Jones & McGrath, Inc., completed its acquisition of RBC Agency, Inc., which had offices in Shawnee and Stillwater. BancFirst Insurance Services, Inc. also has offices in Oklahoma City, Tulsa, Lawton and Muskogee. The acquisition did not have a material effect on the Company's consolidated financial statements. On March 21, 2010, Congress passed student loan reform legislation centralizing student lending in a governmental agency, which as of June 30, 2010 resulted in an end to the student loan programs provided by the Company. The Company sold all student loans held for sale of $144.5 million in October 2010. As of December 31, 2011 and 2010, the Company had no student loans held for sale. See Note (5) for the amount of student loans held for investment. On December 8, 2009, the Company completed the acquisition of First Jones Bancorporation. On November 30, 2009, First State Bank, Jones, the subsidiary bank, had approximately $36 million in assets, $31 million in deposits, and $4.5 million in equity capital. First State Bank, Jones operated as a subsidiary of BancFirst Corporation until it was merged into BancFirst in early March 2010. The acquisition enhanced the presence of BancFirst in eastern Oklahoma County. The acquisition did not have a material effect on the Company's consolidated financial statements. In November 2009, the FDIC issued a rule that required insured depository institutions to prepay their estimated quarterly risk-based assessments for the fourth quarter of 2009 and for all of 2010, 2011 and 2012. In December 2009, the Company paid $20.2 million in prepaid risk-based assessments, which included $1.2 million related to the fourth quarter of 2009 that would have otherwise been payable in the first quarter of 2010. This amount was included in deposit insurance expense for 2009. Prepaid deposit insurance of approximately $12.3 million and $15.0 million was included in other assets in the accompanying consolidated balance sheets for the years ended December 31, 2011 and 2010, respectively. On May 22, 2009 the FDIC increased deposit insurance premiums and imposed a Special Assessment on member financial institutions that was based on June 30, 2009 assets less tier one capital. The amount of $1.9 million was expensed on June 30, 2009.

(2) RECENT DEVELOPMENTS, INCLUDING MERGERS & ACQUISITIONS

On July 12, 2011, the Company completed the acquisition of FBC Financial Corporation and its subsidiary bank, 1st Bank Oklahoma with banking locations in Claremore, Verdigris, and Inola, Oklahoma. The Company paid a premium of $1.5 million above the equity capital of FBC Financial Corporation. At acquisition, 1st Bank Oklahoma had approximately $217 million in total assets, $116 million in loans, $178 million in deposits and $18 million in equity capital. 1st Bank Oklahoma operated as a subsidiary of BancFirst Corporation until it was merged into BancFirst on February 17, 2012. The acquisition did not have a material effect on the Company's consolidated financial statements.

The Federal Reserve enacted a final rule on June 29, 2011 establishing the debit card interchange rate at $0.21 per transaction and five basis points multiplied by the value of the transaction that was effective on October 1, 2011 for banks exceeding $10 billion in assets. Although the rule does not apply directly to the Company, the possible competitive response may have an impact on the Company's pricing of these services.

On December 15, 2010, the Company completed the acquisition of OK Bancorporation, Inc., and its subsidiary bank, The Okemah National Bank. At acquisition, The Okemah National Bank had approximately $73 million in total assets, $32 million in loans, $62 million in deposits, and $9 million in equity capital. The Okemah National Bank operated as a subsidiary of BancFirst Corporation until it was merged into BancFirst on October 21, 2011. The acquisition did not have a material effect on the Company's consolidated financial statements.

On December 10, 2010, the Company completed the acquisition of Exchange Bancshares of Moore, Inc., and its subsidiary bank, Exchange National Bank of Moore. At acquisition, Exchange National Bank of Moore had approximately $147 million in total assets, $47 million in loans, $116 million in deposits, and $10 million in equity capital. Exchange National Bank of Moore operated as a subsidiary of BancFirst Corporation until it was merged into BancFirst on June 17, 2011. The acquisition did not have a material effect on the Company's consolidated financial statements.

On October 8, 2010, the Company completed the acquisition of Union National Bancshares, Inc., and its subsidiary bank, Union Bank of Chandler with offices in Chandler and Tulsa, Oklahoma. At acquisition, Union Bank of Chandler had approximately $134 million in total assets, $90 million in loans, $117 million in deposits, and $15 million in equity capital. Union Bank of Chandler operated as a subsidiary of BancFirst Corporation until it was merged into BancFirst on November 12, 2010. The acquisition did not have a material effect on the Company's consolidated financial statements.

The Company recorded a total of $13.3 million of goodwill and core deposit intangibles as a result of the three acquisitions completed in 2010. The combined acquisitions added approximately $371 million in total assets, $169 million in loans and $295 million in deposits. The effects of these acquisitions were included in the consolidated financial statements of the Company from the date of acquisition forward. The Company does not believe these acquisitions, individually or in aggregate were material to the Company's consolidated financial statements.

Effective as of June 30, 2010, the Company ceased participation in the Transaction Account Guarantee Program ("TAGP") for extended coverage of noninterest-bearing transaction deposit accounts. Accordingly, the standard deposit insurance amount was in effect for the Company's deposit accounts through December 31, 2010. In November 2010, the Federal Deposit Insurance Corporation ("FDIC") issued a final rule to implement provisions of the Dodd-Frank Act that provide for temporary unlimited coverage for noninterest-bearing transaction accounts. The separate coverage for noninterest-bearing transaction accounts became effective on December 31, 2010 and terminates on December 31, 2012.

On April 1, 2010, the Company's insurance agency BancFirst Insurance Services, Inc., formerly known as Wilcox, Jones & McGrath, Inc., completed its acquisition of RBC Agency, Inc., which had offices in Shawnee and Stillwater. BancFirst Insurance Services, Inc. also has offices in Oklahoma City, Tulsa, Lawton and Muskogee. The acquisition did not have a material effect on the Company's consolidated financial statements.

On March 21, 2010, Congress passed student loan reform legislation centralizing student lending in a governmental agency, which as of June 30, 2010 resulted in an end to the student loan programs provided by the Company. The Company sold all student loans held for sale of $144.5 million in October 2010. As of December 31, 2011 and 2010, the Company had no student loans held for sale. See Note (5) for the amount of student loans held for investment.

On December 8, 2009, the Company completed the acquisition of First Jones Bancorporation. On November 30, 2009, First State Bank, Jones, the subsidiary bank, had approximately $36 million in assets, $31 million in deposits, and $4.5 million in equity capital. First State Bank, Jones operated as a subsidiary of BancFirst Corporation until it was merged into BancFirst in early March 2010. The acquisition enhanced the presence of BancFirst in eastern Oklahoma County. The acquisition did not have a material effect on the Company's consolidated financial statements.

In November 2009, the FDIC issued a rule that required insured depository institutions to prepay their estimated quarterly risk-based assessments for the fourth quarter of 2009 and for all of 2010, 2011 and 2012. In December 2009, the Company paid $20.2 million in prepaid risk-based assessments, which included $1.2 million related to the fourth quarter of 2009 that would have otherwise been payable in the first quarter of 2010. This amount was included in deposit insurance expense for 2009. Prepaid deposit insurance of approximately $12.3 million and $15.0 million was included in other assets in the accompanying consolidated balance sheets for the years ended December 31, 2011 and 2010, respectively.

On May 22, 2009 the FDIC increased deposit insurance premiums and imposed a Special Assessment on member financial institutions that was based on June 30, 2009 assets less tier one capital. The amount of $1.9 million was expensed on June 30, 2009.