Fair Value of Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended		12 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012
Fair Value of Financial Instruments
Cost to assume off-balance sheet commitments and standby letters of credit as a percentage of notional amount	10.00%
Assets:
Securities available for sale	$ 313,047	$ 146,134	$ 84,066
Other real estate owned	1,186	9,339	2,258
Accrued interest receivable	5,766	3,968	4,126
Off-balance sheet commitments and standby letters of credit
Notional Amount	236,425	126,544	131,450
Cost to Cede or Assume	23,643	12,654	13,145
Level 1
Assets:
Cash and cash equivalents	103,972	64,972	59,352
Securities available for sale	206,226	102,004	81,042
Federal Reserve Bank and FHLB stock, at cost	11,917	12,744	11,247
Accrued interest receivable	5,766	3,968	4,126
Liabilities:
Deposit accounts	978,117	477,661	548,101
FHLB advances			87,000
Accrued interest payable	213	151	142
Level 2
Assets:
Securities available for sale	105,764	43,203	2,072
Loans held for sale, net	3,617	2,401	3,681
Liabilities:
Deposit accounts	336,238	439,328	363,382
Other borrowings	50,074	32,177	31,267
Subordinated debentures	4,818	7,513	4,973
Off-balance sheet commitments and standby letters of credit
Cost to Cede or Assume	23,643	12,654	13,145
Level 3
Assets:
Securities available for sale	1,057	927	952
Loans held for investment, net	1,124,670	869,751	1,049,589
Carrying Amount
Assets:
Cash and cash equivalents	103,972	64,972	59,352
Securities available for sale	313,047	146,134	84,066
Federal Reserve Bank and FHLB stock, at cost	11,917	12,744	11,247
Loans held for sale, net	3,617	2,401	3,681
Loans held for investment, net	1,047,436	787,661	974,213
Accrued interest receivable	5,766	3,968	4,126
Liabilities:
Deposit accounts	1,314,189	913,191	904,768
FHLB advances			87,000
Other borrowings	48,082	28,500	28,500
Subordinated debentures	10,310	10,310	10,310
Accrued interest payable	213	151	142
Estimated Fair Value
Assets:
Cash and cash equivalents	103,972	64,972	59,352
Securities available for sale	313,047	146,134	84,066
Federal Reserve Bank and FHLB stock, at cost	11,917	12,744	11,247
Loans held for sale, net	3,617	2,401	3,681
Loans held for investment, net	1,124,670	869,751	1,049,589
Accrued interest receivable	5,766	3,968	4,126
Liabilities:
Deposit accounts	1,314,355	916,989	911,483
FHLB advances			87,000
Other borrowings	50,074	32,177	31,267
Subordinated debentures	4,818	7,513	4,973
Accrued interest payable	$ 213	$ 151	$ 142