Disclosures About Fair Value of Financial Instruments - Balance Sheet Grouping (Details 3) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Available-for-sale securities	$ 204,880	$ 187,565
Held-to-maturity securities	44,901	50,725
Loans held for sale	192	573
Loans held for investment	1,982,280	1,799,155	$ 1,504,998
Real estate acquired by foreclosure	1,665	4,863
Level 1 [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Cash and short term investments	96,451	68,923
Available-for-sale securities	80,140	27,035
Other securities	16,977	11,365
Loans held for sale	192	573
Total	193,760	107,896
Level 2 [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Available-for-sale securities	124,740	160,530
Held-to-maturity securities	44,901	50,725
Total	169,641	211,255
Financial Liabilities:
Deposits	1,945,896	1,849,281
Securities sold under agreements to repurchase	3,080	4,605
Other borrowed funds	158,902	47,561
Total	2,107,878	1,901,447
Level 3 [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Loans held for investment	2,000,526	1,788,454
Real estate acquired by foreclosure	1,665	4,863
Total	2,002,191	1,793,317
Carrying Value [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Cash and short term investments	96,451	68,923
Available-for-sale securities	204,880	187,565
Held-to-maturity securities	44,678	50,713
Other securities	16,977	11,365
Loans held for sale	192	573
Loans held for investment	1,982,280	1,799,155
Real estate acquired by foreclosure	1,665	4,863
Total	2,347,123	2,123,157
Financial Liabilities:
Deposits	1,941,140	1,845,713
Securities sold under agreements to repurchase	3,080	4,605
Other borrowed funds	158,893	47,586
Total	2,103,113	1,897,904
Fair Value [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Cash and short term investments	96,451	68,923
Available-for-sale securities	204,880	187,565
Held-to-maturity securities	44,901	50,725
Other securities	16,977	11,365
Loans held for sale	192	573
Loans held for investment	2,000,526	1,788,454
Real estate acquired by foreclosure	1,665	4,863
Total	2,365,592	2,112,468
Financial Liabilities:
Deposits	1,945,896	1,849,281
Securities sold under agreements to repurchase	3,080	4,605
Other borrowed funds	158,902	47,561
Total	$ 2,107,878	$ 1,901,447