Loans and Allowance for Loan Losses (Details) - USD ($)		9 Months Ended			12 Months Ended
		Sep. 30, 2015		Sep. 30, 2014	Dec. 31, 2014
Loans and Allowance for Loan Losses [Abstract]
Percentage of loan portfolio as commercial loan		74.00%
Risk rated loans		$ 500,000
Financing Receivable, Recorded Investment [Line Items]
Loans		6,335,988,628			$ 4,590,026,505
Potential problem loans not included in nonperforming assets		91,200,000			83,000,000
Average balance of impaired loans		34,347,000			17,463,000
Estimated increase in interest income if nonaccrual loans had been on accrual status		480,000		$ 682,000
Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		2,192,151,000			1,544,091,000
Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		1,044,276,000			721,158,000
Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		674,926,000			322,466,000
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		2,178,535,000			1,784,729,000
Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		246,101,000			217,583,000
Accruing Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		6,297,567,000			4,564,911,000	[1]
Accruing Loans [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		2,184,696,000			1,539,778,000	[1]
Accruing Loans [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		1,031,078,000			712,774,000	[1]
Accruing Loans [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		668,428,000			316,857,000	[1]
Accruing Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		2,173,201,000			1,779,347,000	[1]
Accruing Loans [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		240,164,000			216,155,000	[1]
Accruing Loans [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		6,133,272,000			4,425,035,000
Accruing Loans [Member] | Pass [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		2,138,361,000			1,510,718,000
Accruing Loans [Member] | Pass [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		1,015,126,000			697,607,000
Accruing Loans [Member] | Pass [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		659,275,000			295,645,000
Accruing Loans [Member] | Pass [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		2,081,298,000			1,704,910,000
Accruing Loans [Member] | Pass [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		239,212,000			216,155,000
Accruing Loans [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		73,061,000			56,837,000
Accruing Loans [Member] | Special Mention [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		21,038,000			7,353,000
Accruing Loans [Member] | Special Mention [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		3,196,000			2,536,000
Accruing Loans [Member] | Special Mention [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		5,348,000			15,215,000
Accruing Loans [Member] | Special Mention [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		42,527,000			31,733,000
Accruing Loans [Member] | Special Mention [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		952,000			0
Accruing Loans [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[1]	91,234,000			83,039,000
Accruing Loans [Member] | Substandard [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[1]	25,297,000			21,707,000
Accruing Loans [Member] | Substandard [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[1]	12,756,000			12,631,000
Accruing Loans [Member] | Substandard [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[1]	3,805,000			5,997,000
Accruing Loans [Member] | Substandard [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[1]	49,376,000			42,704,000
Accruing Loans [Member] | Substandard [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[1]	0			0
Nonaccrual Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		30,049,000	[2]		16,705,000
Nonaccrual Loans [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		7,232,000	[2]		4,313,000
Nonaccrual Loans [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		9,421,000	[2]		4,458,000
Nonaccrual Loans [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		6,498,000	[2]		5,173,000
Nonaccrual Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		1,122,000	[2]		1,609,000
Nonaccrual Loans [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		5,776,000	[2]		1,152,000
Nonaccrual Loans [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		30,049,000	[2]		16,705,000
Nonaccrual Loans [Member] | Substandard [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		7,232,000	[2]		4,313,000
Nonaccrual Loans [Member] | Substandard [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		9,421,000	[2]		4,458,000
Nonaccrual Loans [Member] | Substandard [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		6,498,000	[2]		5,173,000
Nonaccrual Loans [Member] | Substandard [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		1,122,000	[2]		1,609,000
Nonaccrual Loans [Member] | Substandard [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		5,776,000	[2]		1,152,000
Nonaccrual Loans [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		0	[2]		0
Nonaccrual Loans [Member] | Doubtful [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		0	[2]		0
Nonaccrual Loans [Member] | Doubtful [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		0	[2]		0
Nonaccrual Loans [Member] | Doubtful [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		0	[2]		0
Nonaccrual Loans [Member] | Doubtful [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		0	[2]		0
Nonaccrual Loans [Member] | Doubtful [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		0	[2]		0
Troubled Debt Restructurings [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	8,373,000			8,411,000
Troubled Debt Restructurings [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	223,000			0
Troubled Debt Restructurings [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	3,777,000			3,926,000
Troubled Debt Restructurings [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	0			436,000
Troubled Debt Restructurings [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	4,212,000			3,773,000
Troubled Debt Restructurings [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	161,000			276,000
Troubled Debt Restructurings [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	1,410,000			1,148,000
Troubled Debt Restructurings [Member] | Pass [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	223,000			0
Troubled Debt Restructurings [Member] | Pass [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	414,000			62,000
Troubled Debt Restructurings [Member] | Pass [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	0			436,000
Troubled Debt Restructurings [Member] | Pass [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	612,000			575,000
Troubled Debt Restructurings [Member] | Pass [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	161,000			75,000
Troubled Debt Restructurings [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	440,000			1,012,000
Troubled Debt Restructurings [Member] | Special Mention [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	0			0
Troubled Debt Restructurings [Member] | Special Mention [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	440,000			811,000
Troubled Debt Restructurings [Member] | Special Mention [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	0			0
Troubled Debt Restructurings [Member] | Special Mention [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	0			0
Troubled Debt Restructurings [Member] | Special Mention [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	0			201,000
Troubled Debt Restructurings [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	6,523,000			6,251,000
Troubled Debt Restructurings [Member] | Substandard [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	0			0
Troubled Debt Restructurings [Member] | Substandard [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	2,923,000			3,053,000
Troubled Debt Restructurings [Member] | Substandard [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	0			0
Troubled Debt Restructurings [Member] | Substandard [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	3,600,000			3,198,000
Troubled Debt Restructurings [Member] | Substandard [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	0			0
Impaired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	38,422,000			25,116,000
Impaired Loans [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	7,455,000			4,313,000
Impaired Loans [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	13,198,000			8,384,000
Impaired Loans [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	6,498,000			5,609,000
Impaired Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	5,334,000			5,382,000
Impaired Loans [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[3]	5,937,000			$ 1,428,000
Acquired Accruing Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Fair value adjustment		(23,891,000)
Net total acquired loans		1,243,291,000
Acquired Accruing Loans [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		475,428,000
Acquired Accruing Loans [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		292,572,000
Acquired Accruing Loans [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		201,558,000
Acquired Accruing Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		280,508,000
Acquired Accruing Loans [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		17,116,000
Acquired Accruing Loans [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Fair value adjustment		(22,265,000)
Net total acquired loans		1,215,453,000
Acquired Accruing Loans [Member] | Pass [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		462,538,000
Acquired Accruing Loans [Member] | Pass [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		288,074,000
Acquired Accruing Loans [Member] | Pass [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		196,765,000
Acquired Accruing Loans [Member] | Pass [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		274,210,000
Acquired Accruing Loans [Member] | Pass [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		16,131,000
Acquired Accruing Loans [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Fair value adjustment		(1,092,000)
Net total acquired loans		17,261,000
Acquired Accruing Loans [Member] | Special Mention [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		5,017,000
Acquired Accruing Loans [Member] | Special Mention [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		3,355,000
Acquired Accruing Loans [Member] | Special Mention [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		3,800,000
Acquired Accruing Loans [Member] | Special Mention [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		5,196,000
Acquired Accruing Loans [Member] | Special Mention [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		985,000
Acquired Accruing Loans [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Fair value adjustment		(534,000)
Net total acquired loans		10,577,000
Acquired Accruing Loans [Member] | Substandard [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		7,873,000
Acquired Accruing Loans [Member] | Substandard [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		1,143,000
Acquired Accruing Loans [Member] | Substandard [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		993,000
Acquired Accruing Loans [Member] | Substandard [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		1,102,000
Acquired Accruing Loans [Member] | Substandard [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		0
Acquired Nonaccrual Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Fair value adjustment	[4]	(4,939,000)
Net total acquired loans	[4]	11,759,000
Acquired Nonaccrual Loans [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[4]	5,449,000
Acquired Nonaccrual Loans [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[4]	5,012,000
Acquired Nonaccrual Loans [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[4]	3,781,000
Acquired Nonaccrual Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[4]	1,796,000
Acquired Nonaccrual Loans [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[4]	660,000
Acquired Nonaccrual Loans [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Fair value adjustment	[4]	(4,939,000)
Net total acquired loans	[4]	11,759,000
Acquired Nonaccrual Loans [Member] | Substandard [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[4]	5,449,000
Acquired Nonaccrual Loans [Member] | Substandard [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[4]	5,012,000
Acquired Nonaccrual Loans [Member] | Substandard [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[4]	3,781,000
Acquired Nonaccrual Loans [Member] | Substandard [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[4]	1,796,000
Acquired Nonaccrual Loans [Member] | Substandard [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[4]	660,000
Acquired Nonaccrual Loans [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Fair value adjustment	[4]	0
Net total acquired loans	[4]	0
Acquired Nonaccrual Loans [Member] | Doubtful [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[4]	0
Acquired Nonaccrual Loans [Member] | Doubtful [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[4]	0
Acquired Nonaccrual Loans [Member] | Doubtful [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[4]	0
Acquired Nonaccrual Loans [Member] | Doubtful [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[4]	0
Acquired Nonaccrual Loans [Member] | Doubtful [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[4]	0
Acquired Impaired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Fair value adjustment	[4]	(4,939,000)
Net total acquired loans	[4]	11,759,000
Acquired Impaired Loans [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[4]	5,449,000
Acquired Impaired Loans [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[4]	5,012,000
Acquired Impaired Loans [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[4]	3,781,000
Acquired Impaired Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[4]	1,796,000
Acquired Impaired Loans [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	[4]	660,000
Acquired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		1,284,000,000
Fair value adjustment		(28,830,000)
Net total acquired loans		1,255,050,000
Acquired Loans [Member] | CapitalMark Bank & Trust [Member]
Financing Receivable, Recorded Investment [Line Items]
Net total acquired loans		816,500,000
Acquired Loans [Member] | Magna Bank [Member]
Financing Receivable, Recorded Investment [Line Items]
Net total acquired loans		439,500,000
Acquired Loans [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		480,877,000
Acquired Loans [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		297,584,000
Acquired Loans [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		205,339,000
Acquired Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		282,304,000
Acquired Loans [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans		$ 17,776,000

[1] Potential problem loans represent those loans with a well-defined weakness and where information about possible credit problems of borrowers has caused management to have doubts about the borrower's ability to comply with present repayment terms. This definition is believed to be substantially consistent with the standards established by Pinnacle Bank's primary regulators for loans classified as substandard, excluding the impact of nonaccrual loans and troubled debt restructurings. Potential problem loans, which are not included in nonaccrual loans, amounted to approximately $91.2 million at September 30, 2015, compared to $83.0 million at December 31, 2014.

[2] Included in nonaccrual loans at September 30, 2015 are $11.8 million in loans acquired with deteriorated credit quality.

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

[4] All of the acquired impaired loans have been deemed to be collateral dependent and as such were placed on nonaccrual. As such, no accretable difference has been recorded on these loans.