Loans (Nonaccrual Status) (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Financing Receivable, Recorded Investment, Past Due [Line Items]
Interest lost on nonaccrual loans	$ 1,500,000	$ 3,500,000	$ 2,900,000	$ 7,600,000
Loans on nonaccrual status	85,100,000		85,100,000		103,000,000
90 or more days past due and accruing	1,071,000		1,071,000		3,000,000
Net loans held for investment	1,200,936,000		1,200,936,000		1,178,175,000
Commercial and agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 or more days past due and accruing	671,000		671,000		305,000
Real estate - construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 or more days past due and accruing	0		0		1,400,000
Real estate - mortgage, 1-4 family residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 or more days past due and accruing	58,000		58,000		292,000
Real estate - mortgage, commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 or more days past due and accruing	339,000		339,000		1,003,000
Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
90 or more days past due and accruing	3,000		3,000		0
Nonperforming [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment on nonaccrual status	85,072,000		85,072,000		98,444,000
90 or more days past due and accruing	1,071,000		1,071,000		3,000,000
Net loans held for investment	86,143,000		86,143,000		101,444,000
Loans held for sale on nonaccrual status	0		0		4,529,000
Nonperforming [Member] | Commercial and agricultural [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment on nonaccrual status	2,476,000		2,476,000		4,636,000
Nonperforming [Member] | Real estate - construction [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment on nonaccrual status	18,506,000		18,506,000		30,844,000
Loans held for sale on nonaccrual status	0		0		1,807,000
Nonperforming [Member] | Real estate - mortgage, 1-4 family residential [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment on nonaccrual status	22,073,000		22,073,000		26,048,000
Loans held for sale on nonaccrual status	0		0		517,000
Nonperforming [Member] | Real estate - mortgage, commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment on nonaccrual status	41,794,000		41,794,000		36,666,000
Loans held for sale on nonaccrual status	0		0		2,205,000
Nonperforming [Member] | Consumer [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Loans held for investment on nonaccrual status	223,000		223,000		250,000
Loans held for sale on nonaccrual status	$ 0		$ 0		$ 0