Summary of Significant Accounting Policies (Details) (USD $)	3 Months Ended												12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash Equivalents and Cash Flows [Abstract]
Cash equivalents maturity period	90 days												90 days
Cash Payments [Abstract]
Interest													$ 23,506,632	$ 39,991,746	$ 60,675,865
Income taxes paid (refunded)													10,249,106	3,988,414	(4,722,776)
Noncash Transactions:
Loans charged-off to the allowance for loan losses													19,657,061	34,849,910	67,543,395
Loans foreclosed upon and transferred to other real estate owned													9,052,792	34,580,351	92,873,551
Loans [Abstract]
Number of loan segments													5
Net deferred loan fees													1,000,000	315,000
Percentage of loan portfolio assigned specific risk rating (in hundredths)	77.00%												77.00%
Number of loans classified as nonaccrual loans	0												0
ASC 450-20, Loss Contingencies [Abstract]
Loss allocation rate from migration analysis (in hundredths)	75.00%												75.00%
Loss allocation rates for industry loss allocation (in hundredths)	25.00%												25.00%
Number of prior quarters used for historical migration analysis													15		8
Allowance for loan loss accounted for by environmental factors (in hundredths)													18.60%	8.80%
Financing Receivable, Impaired [Line Items]
Principal balance of loans subject to individual determination of impairment	250,000												250,000
Impaired loans with valuation allowance based on allocated rate calculated for similar loan	250,000												250,000
Amount of collateral dependent loans reviewed to determine charged-off amount	250,000												250,000
Principal balance of impaired loans	22,823,000				47,855,000				80,863,000				22,823,000	47,855,000	80,863,000
Premises and Equipment and Leaseholds [Abstract]
Deferred liability associated with escalating rentals	2,015,000												2,015,000
Other Assets [Abstract]
Computer software related assets, net	75,804,895				77,127,361								75,804,895	77,127,361
Cash surrender value of life insurance	49,802,000				48,883,000								49,802,000	48,883,000
Noninterest income related to cash surrender value of bank owned life insurance policies													919,000	1,159,000	913,000
Loan participations sold to correspondent bank	468,000				498,000								468,000	498,000
Pre-paid deposit insurance is included in other assets	4,100,000												4,100,000
Variable Interest Entity [Line Items]
Federal Reserve Bank and Federal Home Loan Bank (FHLB) stock	14,176,000				32,861,000								14,176,000	32,861,000
Investments in other entities at fair value	4,214,000				3,400,000								4,214,000	3,400,000
Gain (loss) due to change in fair value of investments													(70,000)	314,000
Number of trusts investment	4												4
Value of investments with trust companies	26,962,890				44,653,840								26,962,890	44,653,840
Investments as per community reinvestment act	6,096,000				5,917,000								6,096,000	5,917,000
Other Real Estate Owned [Abstract]
Other real estate owned	26,793,000				52,711,000								26,793,000	52,711,000
Valuation allowance related to other real estate owned	8,213,000				12,997,000								8,213,000	12,997,000
Foreclosed real estate expense													11,544,000	17,432,000	29,210,000
Realized losses on foreclosed real estate													9,470,000	12,806,000	25,732,000
Investment Services and Trust Fees [Abstract]
Brokerage assets under management													1,240,000,000	1,060,000,000
Trust assets under management	819,000,000				633,000,000								819,000,000	633,000,000
Advertising [Abstract]
Advertising expense													447,000	339,000	259,000
Income Tax [Abstract]
Unrecognized tax benefits	0												0
Income Tax Contingency [Line Items]
Uncertain tax positions accrued interest	0												0
Uncertain tax positions accrued penalties	0												0
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock options, stock appreciation rights and warrants included in earning per share calculation (in shares)													588,000	640,000
Antidilutive securities excluded from computation of earnings per share (in shares)													1,208,332	730,300
Basic earnings per share calculation [Abstract]
Numerator - Net income (loss) available to common stockholders	11,730,000	11,349,000	7,785,000	7,206,000	5,681,000	24,537,000	4,844,000	2,011,000	2,248,000	549,000	(27,871,000)	(5,368,000)	38,069,841	37,072,728	(30,442,514)
Denominator - Weighted average common shares outstanding (in shares)													33,899,667	33,420,015	32,789,871
Basic net income (loss) per share available to common stockholders (in dollars per share)	$ 0.35	$ 0.33	$ 0.23	$ 0.21	$ 0.17	$ 0.74	$ 0.14	$ 0.06	$ 0.07	$ 0.02	$ (0.85)	$ (0.16)	$ 1.12	$ 1.11	$ (0.93)
Diluted earnings per share calculation [Abstract]
Numerator - Net income (loss) available to common stockholders	11,730,000	11,349,000	7,785,000	7,206,000	5,681,000	24,537,000	4,844,000	2,011,000	2,248,000	549,000	(27,871,000)	(5,368,000)	38,069,841	37,072,728	(30,442,514)
Denominator - Weighted average common shares outstanding (in shares)													33,899,667	33,420,015	32,789,871
Dilutive shares contingently issuable (in shares)													588,141	640,213	0
Weighted average diluted common shares outstanding (in shares)													34,487,808	34,060,228	32,789,871
Diluted net income (loss) per share available to common stockholders (in dollars per share)	$ 0.34	$ 0.33	$ 0.23	$ 0.21	$ 0.17	$ 0.72	$ 0.14	$ 0.06	$ 0.07	$ 0.02	$ (0.85)	$ (0.16)	$ 1.10	$ 1.09	$ (0.93)
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock options outstanding (in shares)	1,311,000												1,311,000
Stock Appreciation Rights [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock options outstanding (in shares)	7,300												7,300
Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Warrants outstanding (in shares)	267,445												267,445
Trust [Member]
Variable Interest Entity [Line Items]
Value of investments with trust companies	2,476,000				2,476,000								2,476,000	2,476,000
Minimum [Member] | Internal Revenue Service (IRS) [Member]
Income Tax Contingency [Line Items]
Tax year open to audit under the statute of limitation													2008
Minimum [Member] | State of Tennessee [Member]
Income Tax Contingency [Line Items]
Tax year open to audit under the statute of limitation													2009
Maximum [Member] | Internal Revenue Service (IRS) [Member]
Income Tax Contingency [Line Items]
Tax year open to audit under the statute of limitation													2012
Maximum [Member] | State of Tennessee [Member]
Income Tax Contingency [Line Items]
Tax year open to audit under the statute of limitation													2012
Premises and Equipment [Member] | Minimum [Member]
Premises and Equipment and Leaseholds [Abstract]
Premises and equipment, useful life													3 years
Premises and Equipment [Member] | Maximum [Member]
Premises and Equipment and Leaseholds [Abstract]
Premises and equipment, useful life													30 years
Software [Member]
Other Assets [Abstract]
Computer software related assets, net	1,336,000				1,318,000								1,336,000	1,318,000
Amortization													901,000	818,000	754,000
Software [Member] | Minimum [Member]
Other Assets [Abstract]
Computer software related assets, useful life													3 years
Software [Member] | Maximum [Member]
Other Assets [Abstract]
Computer software related assets, useful life													7 years
Loan Participations Sold [Member]
Other Assets [Abstract]
Amortization													30,000	68,000	91,000
Small Impaired Loans [Member]
Financing Receivable, Impaired [Line Items]
Principal balance of impaired loans	$ 5,000,000				$ 10,300,000								$ 5,000,000	$ 10,300,000
Percentage of small impaired loans to total impaired loans (in hundredths)	9.90%				14.30%								9.90%	14.30%