Summary of Significant Accounting Policies (Details) (USD $)	3 Months Ended												12 Months Ended
	Dec. 31, 2014 Trust	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Mar. 31, 2012	Jun. 30, 2011	Dec. 31, 2014 Segment Trust	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash Equivalents and Cash Flows [Abstract]
Cash equivalents maturity period (in days)													90 days
Cash Payments [Abstract]
Interest													$ 13,414,134	$ 16,020,132	$ 23,506,632
Income taxes paid (refunded)													31,350,000	27,150,000	10,249,106
Noncash Transactions:
Loans charged-off to the allowance for loan losses													7,702,661	17,252,736	19,657,061
Loans foreclosed upon and transferred to other real estate owned													4,649,852	4,630,251	9,052,792
Available-for-sale securities transferred to held-to-maturity portfolio													0	39,959,647	0
Loans [Abstract]
Number of loan segments													5
Net deferred loan fees													1,355,658	993,000
Percentage of loan portfolio assigned specific risk rating (in hundredths)	74.00%												74.00%
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													23 months
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	16,705,000				18,183,000				22,823,000				16,705,000	18,183,000	22,823,000
Premises and Equipment and Leaseholds [Abstract]
Deferred liability associated with escalating rentals	2,410,950												2,410,950
Other Assets [Abstract]
Computer software related assets, net	71,576,016				72,649,574								71,576,016	72,649,574
Cash surrender value of life insurance	92,697,419				90,270,972								92,697,419	90,270,972
Noninterest income related to cash surrender value of bank owned life insurance policies													2,426,447	2,116,227	919,000
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	15,800,000				16,100,000								15,800,000	16,100,000
Investments in other entities at fair value	8,000,000				6,700,000								8,000,000	6,700,000
Gain (loss) due to change in fair value of investments													690,000	122,000
Number of trusts investment	4												4
Value of investments with trust companies	38,062,134				33,226,195								38,062,134	33,226,195
Investments as per community reinvestment act	10,769,000				7,945,000								10,769,000	7,945,000
Other Real Estate Owned [Abstract]
Other real estate owned	15,110,860				20,912,785								15,110,860	20,912,785
Valuation allowance related to other real estate owned	3,924,446				5,686,649								3,924,446	5,686,649
Foreclosed real estate expense													664,289	3,113,046	11,544,067
Realized losses on foreclosed real estate													(552,685)	2,014,000	9,470,000
Investment Services and Trust Fees [Abstract]
Brokerage assets under management													1,695,238.00	1,560,349.00
Trust assets under management	764,802.00				605,324.00								764,802.00	605,324.00
Advertising [Abstract]
Advertising expense													439,520	265,455	447,000
Income Tax [Abstract]
Unrecognized tax benefits	391,000				0				0				391,000	0	0	0
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	140,000												140,000
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)													403,555	308,491
Basic earnings per share calculation [Abstract]
Numerator - Net income (loss) available to common stockholders	18,737,000	18,197,000	17,170,000	16,367,000	15,321,000	14,647,000	14,311,000	13,448,000	11,730,000	11,349,000	7,206,000	7,785,000	70,471,167	57,726,201	38,069,841
Denominator - Weighted average common shares outstanding (in shares)													34,723,335	34,200,770	33,899,667
Basic net income (loss) per share available to common stockholders (in dollars per share)	$ 0.54	$ 0.52	$ 0.49	$ 0.47	$ 0.45	$ 0.43	$ 0.42	$ 0.40	$ 0.35	$ 0.33	$ 0.21	$ 0.23	$ 2.03	$ 1.69	$ 1.12
Diluted earnings per share calculation [Abstract]
Numerator - Net income (loss) available to common stockholders	18,737,000	18,197,000	17,170,000	16,367,000	15,321,000	14,647,000	14,311,000	13,448,000	11,730,000	11,349,000	7,206,000	7,785,000	70,471,167	57,726,201	38,069,841
Denominator - Weighted average common shares outstanding (in shares)													34,723,335	34,200,770	33,899,667
Dilutive shares contingently issuable (in shares)													403,555	308,491	588,141
Weighted average diluted common shares outstanding (in shares)													35,126,890	34,509,261	34,487,808
Diluted net income (loss) per share available to common stockholders (in dollars per share)	$ 0.53	$ 0.52	$ 0.49	$ 0.47	$ 0.44	$ 0.42	$ 0.42	$ 0.39	$ 0.34	$ 0.33	$ 0.21	$ 0.23	$ 2.01	$ 1.67	$ 1.10
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock options outstanding (in shares)	695,000												695,000
Stock Appreciation Rights [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Stock options outstanding (in shares)	3,700												3,700
Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Warrants outstanding (in shares)					0									0
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													2011
Minimum [Member] | State of Tennessee [Member]
Income Tax Contingency [Line Items]
Tax year open to audit under the statute of limitation													2011
Maximum [Member] | Internal Revenue Service (IRS) [Member]
Income Tax Contingency [Line Items]
Tax year open to audit under the statute of limitation													2014
Maximum [Member] | State of Tennessee [Member]
Income Tax Contingency [Line Items]
Tax year open to audit under the statute of limitation													2014
Premises and Equipment [Member] | Minimum [Member]
Premises and Equipment and Leaseholds [Abstract]
Premises and equipment, useful life (in years)													3 years
Premises and Equipment [Member] | Maximum [Member]
Premises and Equipment and Leaseholds [Abstract]
Premises and equipment, useful life (in years)													30 years
Software [Member]
Other Assets [Abstract]
Computer software related assets, net	2,294,521				2,748,000								2,294,521	2,748,000
Amortization													1,084,000	937,000	818,000
Software [Member] | Minimum [Member]
Other Assets [Abstract]
Computer software related assets, useful life (in years)													3 years
Software [Member] | Maximum [Member]
Other Assets [Abstract]
Computer software related assets, useful life (in years)													7 years
Small Impaired Loans [Member]
Financing Receivable, Impaired [Line Items]
Principal balance of impaired loans	$ 5,300,000				$ 5,800,000								$ 5,300,000	$ 5,800,000
Percentage of small impaired loans to total impaired loans (in hundredths)	21.00%				15.20%								21.00%	15.20%