Loans and Allowance for Loan Losses, Allowance for Credit Losses (Details) (USD $)	9 Months Ended			12 Months Ended
	Sep. 30, 2014		Sep. 30, 2013	Dec. 31, 2013
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	$ 66,159,575			$ 67,969,693
Changes in allowance for loan losses [Roll Forward]
Beginning Balance	67,970,000		69,417,000	69,417,000
Charged-off loans	(5,634,327)		(14,088,656)	(17,252,000)
Recovery of previously charged-off loans	2,231,000			7,948,000
Provision for loan losses	1,593,000			7,857,000
Ending Balance	66,160,000			67,970,000
Financing Receivable, Individually Evaluated for Impairment	29,258,000			37,829,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	2,793,000			3,973,000
Financing Receivable, Collectively Evaluated for Impairment	4,391,993,000			4,106,664,000
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	59,022,000			59,755,000
Financing Receivable, Acquired with Deteriorated Credit Quality	0			0
Financing Receivable, Allowance for Credit Losses, Acquired with Deteriorated Credit Quality	0			0
Loans and Leases Receivable, Net of Deferred Income	4,421,250,676			4,144,493,486
Loans and other extensions of credit granted to directors, executive officers, and their related entities	6,600,000			11,200,000
Amount drawn from loans and other extensions of credit granted	2,800,000			8,900,000
Loans Sold, Gross, Mortgage	240,761,000,000		349,567,000,000
Mortgage loans held-for-sale	19,130,001			12,850,339
Gain loss on sale of loans held for sale	4,300,000		5,100,000
Commercial Real Estate - Mortgage [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	18,694,000			21,372,000
Changes in allowance for loan losses [Roll Forward]
Beginning Balance	21,372,000		19,634,000	19,634,000
Charged-off loans	(875,000)			(4,123,000)
Recovery of previously charged-off loans	416,000			500,000
Provision for loan losses	(2,219,000)			5,361,000
Ending Balance	18,694,000			21,372,000
Financing Receivable, Individually Evaluated for Impairment	7,486,000			22,470,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	97,000			2,074,000
Financing Receivable, Collectively Evaluated for Impairment	1,471,383,000			1,360,965,000
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	18,597,000			19,298,000
Financing Receivable, Acquired with Deteriorated Credit Quality	0			0
Financing Receivable, Allowance for Credit Losses, Acquired with Deteriorated Credit Quality				0
Loans and Leases Receivable, Net of Deferred Income	1,478,869,000			1,383,435,000
Consumer Real Estate - Mortgage [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	7,381,000			8,355,000
Changes in allowance for loan losses [Roll Forward]
Beginning Balance	8,355,000		8,762,000	8,762,000
Charged-off loans	(1,075,000)			(2,250,000)
Recovery of previously charged-off loans	232,000			1,209,000
Provision for loan losses	(131,000)			634,000
Ending Balance	7,381,000			8,355,000
Financing Receivable, Individually Evaluated for Impairment	10,160,000			9,273,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	1,329,000			1,265,000
Financing Receivable, Collectively Evaluated for Impairment	696,641,000			686,343,000
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	6,052,000			7,090,000
Financing Receivable, Acquired with Deteriorated Credit Quality	0			0
Financing Receivable, Allowance for Credit Losses, Acquired with Deteriorated Credit Quality				0
Loans and Leases Receivable, Net of Deferred Income	706,801,000			695,616,000
Construction and Land Development [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	5,810,000			7,235,000
Changes in allowance for loan losses [Roll Forward]
Beginning Balance	7,235,000		9,164,000	9,164,000
Charged-off loans	(301,000)			(1,351,000)
Recovery of previously charged-off loans	271,000			1,464,000
Provision for loan losses	(1,395,000)			(2,042,000)
Ending Balance	5,810,000			7,235,000
Financing Receivable, Individually Evaluated for Impairment	5,474,000			1,183,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	47,000			49,000
Financing Receivable, Collectively Evaluated for Impairment	316,616,000			315,008,000
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	5,763,000			7,186,000
Financing Receivable, Acquired with Deteriorated Credit Quality	0			0
Financing Receivable, Allowance for Credit Losses, Acquired with Deteriorated Credit Quality				0
Loans and Leases Receivable, Net of Deferred Income	322,090,000			316,191,000
Commercial and Industrial [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	27,284,000			25,134,000
Changes in allowance for loan losses [Roll Forward]
Beginning Balance	25,134,000		24,738,000	24,738,000
Charged-off loans	(2,336,000)			(8,159,000)
Recovery of previously charged-off loans	990,000			4,531,000
Provision for loan losses	3,496,000			4,024,000
Ending Balance	27,284,000			25,134,000
Financing Receivable, Individually Evaluated for Impairment	5,363,000			4,385,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	824,000			474,000
Financing Receivable, Collectively Evaluated for Impairment	1,718,723,000			1,601,162,000
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	26,460,000			24,660,000
Financing Receivable, Acquired with Deteriorated Credit Quality	0			0
Financing Receivable, Allowance for Credit Losses, Acquired with Deteriorated Credit Quality				0
Loans and Leases Receivable, Net of Deferred Income	1,724,086,000			1,605,547,000
Consumer and Other [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	2,646,000			1,632,000
Changes in allowance for loan losses [Roll Forward]
Beginning Balance	1,632,000		1,094,000	1,094,000
Charged-off loans	(1,047,000)			(1,369,000)
Recovery of previously charged-off loans	322,000			244,000
Provision for loan losses	1,739,000			1,663,000
Ending Balance	2,646,000			1,632,000
Financing Receivable, Individually Evaluated for Impairment	775,000			518,000
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment	496,000			111,000
Financing Receivable, Collectively Evaluated for Impairment	188,630,000			143,186,000
Financing Receivable, Allowance for Credit Losses, Collectively Evaluated for Impairment	2,150,000			1,521,000
Financing Receivable, Acquired with Deteriorated Credit Quality	0			0
Financing Receivable, Allowance for Credit Losses, Acquired with Deteriorated Credit Quality				0
Loans and Leases Receivable, Net of Deferred Income	189,405,000			143,704,000
Unallocated [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	4,345,000			4,242,000
Changes in allowance for loan losses [Roll Forward]
Beginning Balance	4,242,000		6,025,000	6,025,000
Charged-off loans	0			0
Recovery of previously charged-off loans	0			0
Provision for loan losses	103,000			(1,783,000)
Ending Balance	4,345,000			4,242,000
Accruing Loans [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	59,022,000			59,755,000
Changes in allowance for loan losses [Roll Forward]
Loans and Leases Receivable, Net of Deferred Income	4,391,993,000			4,106,664,000
Accruing Loans [Member] | Commercial Real Estate - Mortgage [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	18,597,000			19,298,000
Changes in allowance for loan losses [Roll Forward]
Loans and Leases Receivable, Net of Deferred Income	1,471,383,000			1,360,965,000
Accruing Loans [Member] | Consumer Real Estate - Mortgage [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	6,052,000			7,090,000
Changes in allowance for loan losses [Roll Forward]
Loans and Leases Receivable, Net of Deferred Income	696,641,000			686,343,000
Accruing Loans [Member] | Construction and Land Development [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	5,763,000			7,186,000
Changes in allowance for loan losses [Roll Forward]
Loans and Leases Receivable, Net of Deferred Income	316,616,000			315,008,000
Accruing Loans [Member] | Commercial and Industrial [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	26,460,000			24,660,000
Changes in allowance for loan losses [Roll Forward]
Loans and Leases Receivable, Net of Deferred Income	1,718,723,000			1,601,162,000
Accruing Loans [Member] | Consumer and Other [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	2,150,000			1,521,000
Changes in allowance for loan losses [Roll Forward]
Loans and Leases Receivable, Net of Deferred Income	188,630,000			143,186,000
Accruing Loans [Member] | Unallocated [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	0			0
Nonaccrual Loans [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	1,225,000			1,187,000
Changes in allowance for loan losses [Roll Forward]
Loans and Leases Receivable, Net of Deferred Income	21,652,000			18,183,000
Nonaccrual Loans [Member] | Commercial Real Estate - Mortgage [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	62,000			142,000
Changes in allowance for loan losses [Roll Forward]
Loans and Leases Receivable, Net of Deferred Income	7,486,000			9,017,000
Nonaccrual Loans [Member] | Consumer Real Estate - Mortgage [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	571,000			722,000
Changes in allowance for loan losses [Roll Forward]
Loans and Leases Receivable, Net of Deferred Income	6,248,000			5,289,000
Nonaccrual Loans [Member] | Construction and Land Development [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	47,000			33,000
Changes in allowance for loan losses [Roll Forward]
Loans and Leases Receivable, Net of Deferred Income	5,474,000			1,070,000
Nonaccrual Loans [Member] | Commercial and Industrial [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	110,000			218,000
Changes in allowance for loan losses [Roll Forward]
Loans and Leases Receivable, Net of Deferred Income	1,948,000			2,565,000
Nonaccrual Loans [Member] | Consumer and Other [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	435,000			72,000
Changes in allowance for loan losses [Roll Forward]
Loans and Leases Receivable, Net of Deferred Income	496,000			242,000
Nonaccrual Loans [Member] | Unallocated [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	0			0
Troubled Debt Restructurings [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	1,568,000	[1]		2,786,000	[1]
Changes in allowance for loan losses [Roll Forward]
Loans and Leases Receivable, Net of Deferred Income	7,606,000	[2]		19,646,000	[2]
Troubled Debt Restructurings [Member] | Commercial Real Estate - Mortgage [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	35,000	[1]		1,932,000	[1]
Changes in allowance for loan losses [Roll Forward]
Loans and Leases Receivable, Net of Deferred Income	0	[2]		13,453,000	[2]
Troubled Debt Restructurings [Member] | Consumer Real Estate - Mortgage [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	758,000	[1]		543,000	[1]
Changes in allowance for loan losses [Roll Forward]
Loans and Leases Receivable, Net of Deferred Income	3,912,000	[2]		3,984,000	[2]
Troubled Debt Restructurings [Member] | Construction and Land Development [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	0	[1]		16,000	[1]
Changes in allowance for loan losses [Roll Forward]
Loans and Leases Receivable, Net of Deferred Income	0	[2]		113,000	[2]
Troubled Debt Restructurings [Member] | Commercial and Industrial [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	714,000	[1]		256,000	[1]
Changes in allowance for loan losses [Roll Forward]
Loans and Leases Receivable, Net of Deferred Income	3,415,000	[2]		1,820,000	[2]
Troubled Debt Restructurings [Member] | Consumer and Other [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	61,000	[1]		39,000	[1]
Changes in allowance for loan losses [Roll Forward]
Loans and Leases Receivable, Net of Deferred Income	279,000	[2]		276,000	[2]
Troubled Debt Restructurings [Member] | Unallocated [Member]
Allowance allocation by loan classification for accruing and impaired loans [Abstract]
Total Allowance for Loan Losses	$ 0	[1]		$ 0	[1]

[1] Troubled debt restructurings of $7.6 million and $19.6 million as of September 30, 2014 and December 31, 2013, respectively, are classified as impaired loans pursuant to U.S. GAAP; however, these loans continue to accrue interest at contractual rates.

[2] Troubled debt restructurings are presented as impaired loans; however, they continue to accrue interest at contractual rates