Description of Business and Summary of Significant Accounting Policies (Tables) - ASC 326 [Member]

12 Months Ended

Dec. 31, 2020

Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]

Schedule of Impact of ASC 326 Adoption on Allowance for Credit losses on Loans

The Company has not recorded an allowance for credit losses against its available-for-sale securities, as the credit risk is not material. The following table illustrates the impact of ASC 326 on the allowance for credit losses on the Company’s loans as of January 1, 2020.

	January 1, 2020
	As Reported Under      ASC 326		Pre ASC 326 Adoption		Impact of ASC 326 Adoption
	(Dollars in thousands)
BancFirst
Real estate:
Commercial real estate owner occupied	$	2,819	$	5,625	$	(2,806	)
Commercial real estate non-owner occupied		2,851		8,358		(5,507	)
Construction and development < 60 months		1,158		2,214		(1,056	)
Construction residential real estate < 60 months		1,155		1,933		(778	)
Residential real estate first lien		4,861		8,692		(3,831	)
Residential real estate all other		1,359		2,767		(1,408	)
Farmland		1,413		2,821		(1,408	)
Commercial and agricultural non-real estate		26,657		13,462		13,195
Consumer non-real estate		2,630		3,252		(622	)
Oil and gas		537		1,883		(1,346	)
Other loans		2,516		2,632		(116	)
Pegasus Bank		3,087		599		2,488
Allowance for credit losses on loans	$	51,043	$	54,238	$	(3,195	)

Schedule of Portfolio Segments Weighted Average Life, and Measures the Allowance for Credit Losses

The allowance for credit losses is measured on a collective (pool) basis when similar risk characteristics exist. In connection with our adoption of ASC 326, changes were made to our primary portfolio segments to align with the methodology applied in determining the allowance under CECL. The Company has identified the following portfolio segments, which includes the applicable weighted average remaining life, and measures the allowance for credit losses using the vintage loss analysis adjusted for qualitative factors:

Loan Segment	Life (in years)
BancFirst
Real estate:
Commercial real estate owner occupied		9
Commercial real estate non-owner occupied		6
Construction and development < 60 months		3
Construction residential real estate < 60 months		1
Residential real estate first lien		13
Residential real estate all other		6
Farmland		12
Commercial and agricultural non-real estate		3
Consumer non-real estate		4
Oil and gas		1
Other loans		8
Pegasus Bank		4