Loans and Allowance for Loan Losses (Details) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Loans and Allowance for Loan Losses [Abstract]
Percentage of loan portfolio as commercial loan (in hundredths)	74.00%
Risk rated loans	$ 500,000
Financing Receivable, Recorded Investment [Line Items]
Loans	4,590,026,505		4,144,493,486		3,712,162,430
Potential problem loans not included in nonperforming assets	83,000,000		65,000,000
Principal balance of nonaccrual loans	16,705,000	[1]	18,183,000	[1]
Average balance of impaired loans	17,500,000		21,500,000
Estimated increase in interest income if nonaccrual loans had been on accrual status	636,000		375,000		1,400,000
Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,784,729,000		1,605,547,000		1,446,578,000
Principal balance of nonaccrual loans	1,609,000	[1]	2,565,000	[1]
Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	322,466,000		316,191,000		313,552,000
Principal balance of nonaccrual loans	5,173,000	[1]	1,070,000	[1]
Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	721,158,000		695,616,000		679,926,000
Principal balance of nonaccrual loans	4,458,000	[1]	5,289,000	[1]
Commercial Real Estate Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Principal balance of nonaccrual loans	0	[1]	1,267,000	[1]
Commercial Real Estate Owner Occupied [Member]
Financing Receivable, Recorded Investment [Line Items]
Principal balance of nonaccrual loans	4,313,000	[1]	7,750,000	[1]
Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,544,091,000		1,383,435,000		1,178,196,000
Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	217,583,000		143,704,000		93,910,000
Principal balance of nonaccrual loans	1,152,000	[1]	242,000	[1]
Accruing Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	4,564,911,000		4,106,664,000
Accruing Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,779,347,000		1,601,162,000
Accruing Loans [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	316,857,000		315,008,000
Accruing Loans [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	712,774,000		686,343,000
Accruing Loans [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,539,778,000		1,360,965,000
Accruing Loans [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	216,155,000		143,186,000
Accruing Loans [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	4,425,035,000		3,979,630,000
Accruing Loans [Member] | Pass [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,704,910,000		1,557,923,000
Accruing Loans [Member] | Pass [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	295,645,000		275,876,000
Accruing Loans [Member] | Pass [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	697,607,000		670,412,000
Accruing Loans [Member] | Pass [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,510,718,000		1,332,387,000
Accruing Loans [Member] | Pass [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	216,155,000		143,032,000
Accruing Loans [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	56,837,000		62,006,000
Accruing Loans [Member] | Special Mention [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	31,733,000		20,065,000
Accruing Loans [Member] | Special Mention [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	15,215,000		31,835,000
Accruing Loans [Member] | Special Mention [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	2,536,000		1,824,000
Accruing Loans [Member] | Special Mention [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	7,353,000		8,282,000
Accruing Loans [Member] | Special Mention [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	0		0
Accruing Loans [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	83,039,000	[2]	65,028,000	[2]
Accruing Loans [Member] | Substandard [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	42,704,000	[2]	23,174,000	[2]
Accruing Loans [Member] | Substandard [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	5,997,000	[2]	7,297,000	[2]
Accruing Loans [Member] | Substandard [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	12,631,000	[2]	14,107,000	[2]
Accruing Loans [Member] | Substandard [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	21,707,000	[2]	20,296,000	[2]
Accruing Loans [Member] | Substandard [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	0	[2]	154,000	[2]
Impaired Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	25,116,000		37,829,000
Impaired Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	5,382,000		4,385,000
Impaired Loans [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	5,609,000		1,183,000
Impaired Loans [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	8,384,000		9,273,000
Impaired Loans [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	4,313,000		22,470,000
Impaired Loans [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,428,000		518,000
Nonaccrual Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	16,705,000		18,183,000
Nonaccrual Loans [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,609,000		2,565,000
Nonaccrual Loans [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	5,173,000		1,070,000
Nonaccrual Loans [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	4,458,000		5,289,000
Nonaccrual Loans [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	4,313,000		9,017,000
Nonaccrual Loans [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,152,000		242,000
Nonaccrual Loans [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	16,705,000		18,183,000
Nonaccrual Loans [Member] | Substandard [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,609,000		2,565,000
Nonaccrual Loans [Member] | Substandard [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	5,173,000		1,070,000
Nonaccrual Loans [Member] | Substandard [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	4,458,000		5,289,000
Nonaccrual Loans [Member] | Substandard [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	4,313,000		9,017,000
Nonaccrual Loans [Member] | Substandard [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,152,000		242,000
Nonaccrual Loans [Member] | Doubtful [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	0		0
Nonaccrual Loans [Member] | Doubtful [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	0		0
Nonaccrual Loans [Member] | Doubtful [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	0		0
Nonaccrual Loans [Member] | Doubtful [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	0		0
Nonaccrual Loans [Member] | Doubtful [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	0		0
Nonaccrual Loans [Member] | Doubtful [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	0		0
Troubled Debt Restructurings [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	8,411,000	[3]	19,646,000	[3]
Troubled Debt Restructurings [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	3,773,000	[3]	1,820,000	[3]
Troubled Debt Restructurings [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	436,000	[3]	113,000	[3]
Troubled Debt Restructurings [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	3,926,000	[3]	3,984,000	[3]
Troubled Debt Restructurings [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	0	[3]	13,453,000	[3]
Troubled Debt Restructurings [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	276,000	[3]	276,000	[3]
Troubled Debt Restructurings [Member] | Pass [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,148,000	[3]	4,939,000	[3]
Troubled Debt Restructurings [Member] | Pass [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	575,000	[3]	320,000	[3]
Troubled Debt Restructurings [Member] | Pass [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	436,000	[3]	113,000	[3]
Troubled Debt Restructurings [Member] | Pass [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	62,000	[3]	1,666,000	[3]
Troubled Debt Restructurings [Member] | Pass [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	0	[3]	2,564,000	[3]
Troubled Debt Restructurings [Member] | Pass [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	75,000	[3]	276,000	[3]
Troubled Debt Restructurings [Member] | Special Mention [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	1,012,000	[3]	0	[3]
Troubled Debt Restructurings [Member] | Special Mention [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	0	[3]	0	[3]
Troubled Debt Restructurings [Member] | Special Mention [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	0	[3]	0	[3]
Troubled Debt Restructurings [Member] | Special Mention [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	811,000	[3]	0	[3]
Troubled Debt Restructurings [Member] | Special Mention [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	0	[3]	0	[3]
Troubled Debt Restructurings [Member] | Special Mention [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	201,000	[3]	0	[3]
Troubled Debt Restructurings [Member] | Substandard [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	6,251,000	[3]	14,707,000	[3]
Troubled Debt Restructurings [Member] | Substandard [Member] | Commercial and Industrial [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	3,198,000	[3]	1,500,000	[3]
Troubled Debt Restructurings [Member] | Substandard [Member] | Construction and Land Development [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	0	[3]	0	[3]
Troubled Debt Restructurings [Member] | Substandard [Member] | Consumer Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	3,053,000	[3]	2,318,000	[3]
Troubled Debt Restructurings [Member] | Substandard [Member] | Commercial Real Estate - Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	0	[3]	10,889,000	[3]
Troubled Debt Restructurings [Member] | Substandard [Member] | Consumer and Other [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans	$ 0	[3]	$ 0	[3]

[1] Approximately $10.2 million and $10.9 million of nonaccrual loans as of December 31, 2014 and 2013, respectively, are currently performing pursuant to their contractual terms.

[2] 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 substandard nonperforming loans and substandard troubled debt restructurings. Potential problem loans, which are not included in nonperforming assets, amounted to approximately $83.6 million at December 31, 2014 compared to $65.0 million at December 31, 2013.

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