Regulatory Matters - Schedule of Actual Capital Amounts and Ratios (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital (to Risk-Weighted Assets), Actual Amount	$ 475,442	$ 426,532
Tier1 Capital (to Risk-Weighted Assets), Actual Amount	443,481	397,916
Tier1 Capital (to Average Assets), Actual Amount	443,481	397,916
Total Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Amount	203,620
Tier1 Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Amount	101,810
Tier1 Capital (to Average Assets), For Capital Adequacy Purposes, Amount	125,558
Total Capital (to Risk-Weighted Assets), Actual Ratio	19.00%	19.00%
Tier1 Capital (to Risk-Weighted Assets), Actual Ratio	17.00%	17.00%
Tier1 Capital (to Average Assets), Actual Ratio	11.00%	10.00%
Total Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Ratio	8.00%
Tier1 Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Ratio	4.00%
Tier1 Capital (to Average Assets), For Capital Adequacy Purposes, Ratio	3.00%
Abilene [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital (to Risk-Weighted Assets), Actual Amount	376,106	110,120
Tier1 Capital (to Risk-Weighted Assets), Actual Amount	344,335	103,002
Tier1 Capital (to Average Assets), Actual Amount	344,335	103,002
Total Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Amount	202,391
Tier1 Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Amount	101,195
Tier1 Capital (to Average Assets), For Capital Adequacy Purposes, Amount	125,413
Total Capital (to Risk-Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	252,988
Tier1 Capital (to Risk-Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	151,793
Tier1 Capital (to Average Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount	209,021
Total Capital (to Risk-Weighted Assets), Actual Ratio	15.00%	15.00%
Tier1 Capital (to Risk-Weighted Assets), Actual Ratio	14.00%	14.00%
Tier1 Capital (to Average Assets), Actual Ratio	8.00%	8.00%
Total Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Ratio	8.00%
Tier1 Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Ratio	4.00%
Tier1 Capital (to Average Assets), For Capital Adequacy Purposes, Ratio	3.00%
Total Capital (to Risk-Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	10.00%
Tier1 Capital (to Risk-Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	6.00%
Tier1 Capital (to Average Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio	5.00%
San Angelo [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital (to Risk-Weighted Assets), Actual Amount		38,744
Tier1 Capital (to Risk-Weighted Assets), Actual Amount		36,237
Tier1 Capital (to Average Assets), Actual Amount		36,237
Total Capital (to Risk-Weighted Assets), Actual Ratio		18.00%
Tier1 Capital (to Risk-Weighted Assets), Actual Ratio		17.00%
Tier1 Capital (to Average Assets), Actual Ratio		9.00%
Weatherford [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital (to Risk-Weighted Assets), Actual Amount		33,975
Tier1 Capital (to Risk-Weighted Assets), Actual Amount		31,309
Tier1 Capital (to Average Assets), Actual Amount		31,309
Total Capital (to Risk-Weighted Assets), Actual Ratio		16.00%
Tier1 Capital (to Risk-Weighted Assets), Actual Ratio		15.00%
Tier1 Capital (to Average Assets), Actual Ratio		8.00%
Stephenville [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital (to Risk-Weighted Assets), Actual Amount		33,062
Tier1 Capital (to Risk-Weighted Assets), Actual Amount		30,143
Tier1 Capital (to Average Assets), Actual Amount		30,143
Total Capital (to Risk-Weighted Assets), Actual Ratio		14.00%
Tier1 Capital (to Risk-Weighted Assets), Actual Ratio		13.00%
Tier1 Capital (to Average Assets), Actual Ratio		9.00%
Southlake [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital (to Risk-Weighted Assets), Actual Amount		31,753
Tier1 Capital (to Risk-Weighted Assets), Actual Amount		29,126
Tier1 Capital (to Average Assets), Actual Amount		29,126
Total Capital (to Risk-Weighted Assets), Actual Ratio		15.00%
Tier1 Capital (to Risk-Weighted Assets), Actual Ratio		14.00%
Tier1 Capital (to Average Assets), Actual Ratio		9.00%
Minimum [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Amount		182,050
Tier1 Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Amount		91,025
Tier1 Capital (to Average Assets), For Capital Adequacy Purposes, Amount		115,610
Total Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Ratio		8.00%
Tier1 Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Ratio		4.00%
Tier1 Capital (to Average Assets), For Capital Adequacy Purposes, Ratio		3.00%
Minimum [Member] | Abilene [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Amount		56,943
Tier1 Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Amount		28,472
Tier1 Capital (to Average Assets), For Capital Adequacy Purposes, Amount		38,902
Total Capital (to Risk-Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount		71,179
Tier1 Capital (to Risk-Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount		42,707
Tier1 Capital (to Average Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount		64,837
Total Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Ratio		8.00%
Tier1 Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Ratio		4.00%
Tier1 Capital (to Average Assets), For Capital Adequacy Purposes, Ratio		3.00%
Total Capital (to Risk-Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio		10.00%
Tier1 Capital (to Risk-Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio		6.00%
Tier1 Capital (to Average Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio		5.00%
Minimum [Member] | San Angelo [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Amount		16,988
Tier1 Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Amount		8,494
Tier1 Capital (to Average Assets), For Capital Adequacy Purposes, Amount		11,679
Total Capital (to Risk-Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount		21,235
Tier1 Capital (to Risk-Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount		12,741
Tier1 Capital (to Average Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount		19,465
Total Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Ratio		8.00%
Tier1 Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Ratio		4.00%
Tier1 Capital (to Average Assets), For Capital Adequacy Purposes, Ratio		3.00%
Total Capital (to Risk-Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio		10.00%
Tier1 Capital (to Risk-Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio		6.00%
Tier1 Capital (to Average Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio		5.00%
Minimum [Member] | Weatherford [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Amount		16,894
Tier1 Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Amount		8,447
Tier1 Capital (to Average Assets), For Capital Adequacy Purposes, Amount		11,126
Total Capital (to Risk-Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount		21,117
Tier1 Capital (to Risk-Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount		12,670
Tier1 Capital (to Average Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount		18,544
Total Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Ratio		8.00%
Tier1 Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Ratio		4.00%
Tier1 Capital (to Average Assets), For Capital Adequacy Purposes, Ratio		3.00%
Total Capital (to Risk-Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio		10.00%
Tier1 Capital (to Risk-Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio		6.00%
Tier1 Capital (to Average Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio		5.00%
Minimum [Member] | Stephenville [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Amount		18,488
Tier1 Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Amount		9,244
Tier1 Capital (to Average Assets), For Capital Adequacy Purposes, Amount		10,148
Total Capital (to Risk-Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount		23,109
Tier1 Capital (to Risk-Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount		13,866
Tier1 Capital (to Average Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount		16,914
Total Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Ratio		8.00%
Tier1 Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Ratio		4.00%
Tier1 Capital (to Average Assets), For Capital Adequacy Purposes, Ratio		3.00%
Total Capital (to Risk-Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio		10.00%
Tier1 Capital (to Risk-Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio		6.00%
Tier1 Capital (to Average Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio		5.00%
Minimum [Member] | Southlake [Member]
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Total Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Amount		16,570
Tier1 Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Amount		8,285
Tier1 Capital (to Average Assets), For Capital Adequacy Purposes, Amount		9,225
Total Capital (to Risk-Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount		20,713
Tier1 Capital (to Risk-Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount		12,428
Tier1 Capital (to Average Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Amount		$ 15,375
Total Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Ratio		8.00%
Tier1 Capital (to Risk-Weighted Assets), For Capital Adequacy Purposes, Ratio		4.00%
Tier1 Capital (to Average Assets), For Capital Adequacy Purposes, Ratio		3.00%
Total Capital (to Risk-Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio		10.00%
Tier1 Capital (to Risk-Weighted Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio		6.00%
Tier1 Capital (to Average Assets), To Be Well Capitalized Under Prompt Corrective Action Provisions, Ratio		5.00%