Loans and Allowance for Loan Losses, Financing Receivables Past Due (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 To 89 days past due and performing	$ 10,877,000	$ 11,084,000
90 days or more past due and performing	0	858,000
Total past due and performing	10,877,000	11,942,000
Nonperforming(1)	22,823,000	47,855,000
Current and performing	3,678,462,000	3,231,554,000
Total Loans	3,712,162,000	3,291,351,000
Currently performing impaired loans	9,400,000	25,500,000
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 To 89 days past due and performing	2,549,000	648,000
90 days or more past due and performing	0	604,000
Total past due and performing	2,549,000	1,252,000
Nonperforming(1)	3,038,000	11,890,000
Current and performing	1,440,991,000	1,132,593,000
Total Loans	1,446,578,000	1,145,735,000
Construction and Land Development [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 To 89 days past due and performing	3,511,000	1,572,000
90 days or more past due and performing	0	0
Total past due and performing	3,511,000	1,572,000
Nonperforming(1)	4,509,000	12,965,000
Current and performing	305,532,000	259,711,000
Total Loans	313,552,000	274,248,000
Unallocated [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 To 89 days past due and performing	41,000	3,260,000
90 days or more past due and performing	0	0
Total past due and performing	41,000	3,260,000
Nonperforming(1)	1,200,000	3,227,000
Current and performing	582,554,000	522,505,000
Total Loans	583,795,000	528,992,000
Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 To 89 days past due and performing	462,000	2,489,000
90 days or more past due and performing	0	0
Total past due and performing	462,000	2,489,000
Nonperforming(1)	8,091,000	6,735,000
Current and performing	585,848,000	572,746,000
Total Loans	594,401,000	581,970,000
Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 To 89 days past due and performing	3,870,000	2,589,000
90 days or more past due and performing	0	254,000
Total past due and performing	3,870,000	2,843,000
Nonperforming(1)	5,906,000	12,487,000
Current and performing	670,150,000	680,415,000
Total Loans	679,926,000	695,745,000
Consumer and Other [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
30 To 89 days past due and performing	444,000	526,000
90 days or more past due and performing	0	0
Total past due and performing	444,000	526,000
Nonperforming(1)	79,000	551,000
Current and performing	93,387,000	63,584,000
Total Loans	$ 93,910,000	$ 64,661,000