Loans and Allowance for Loan Losses - Loan Classification by Risk Rating Category (Details) - USD ($)		Jun. 30, 2017	Dec. 31, 2016
Financing Receivable, Recorded Investment [Line Items]
Loans		$ 14,758,764,516	$ 8,449,924,736
Potential problem loans not included in nonperforming assets		182,500,000	114,600,000
BNC Bancorp
Financing Receivable, Recorded Investment [Line Items]
Loans		5,638,333,000
BNC Bancorp | Fair value adjustment
Financing Receivable, Recorded Investment [Line Items]
Loans		(172,706,000)
Pass
Financing Receivable, Recorded Investment [Line Items]
Loans		14,299,977,000	8,242,805,000
Pass | BNC Bancorp
Financing Receivable, Recorded Investment [Line Items]
Loans		5,401,830,000
Pass | BNC Bancorp | Fair value adjustment
Financing Receivable, Recorded Investment [Line Items]
Loans		(143,783,000)
Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans		221,867,000	52,464,000
Special Mention | BNC Bancorp
Financing Receivable, Recorded Investment [Line Items]
Loans		145,226,000
Special Mention | BNC Bancorp | Fair value adjustment
Financing Receivable, Recorded Investment [Line Items]
Loans		(5,111,000)
Substandard-accrual
Financing Receivable, Recorded Investment [Line Items]
Loans	[1]	196,705,000	127,079,000
Substandard-accrual | BNC Bancorp
Financing Receivable, Recorded Investment [Line Items]
Loans	[1]	72,738,000
Substandard-accrual | BNC Bancorp | Fair value adjustment
Financing Receivable, Recorded Investment [Line Items]
Loans	[1]	(16,335,000)
Substandard-nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Loans		39,387,000	27,574,000
Substandard-nonaccrual | BNC Bancorp
Financing Receivable, Recorded Investment [Line Items]
Loans		17,708,000
Substandard-nonaccrual | BNC Bancorp | Fair value adjustment
Financing Receivable, Recorded Investment [Line Items]
Loans		(7,257,000)
Doubtful-nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Loans		829,000	3,000
Doubtful-nonaccrual | BNC Bancorp
Financing Receivable, Recorded Investment [Line Items]
Loans		831,000
Doubtful-nonaccrual | BNC Bancorp | Fair value adjustment
Financing Receivable, Recorded Investment [Line Items]
Loans		(220,000)
Commercial real estate - mortgage
Financing Receivable, Recorded Investment [Line Items]
Loans		6,387,372,000	3,193,496,000
Commercial real estate - mortgage | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans		3,159,457,000
Commercial real estate - mortgage | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans		6,192,533,000	3,137,452,000
Commercial real estate - mortgage | Pass | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans		3,029,203,000
Commercial real estate - mortgage | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans		112,120,000	21,449,000
Commercial real estate - mortgage | Special Mention | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans		73,517,000
Commercial real estate - mortgage | Substandard-accrual
Financing Receivable, Recorded Investment [Line Items]
Loans	[1]	72,603,000	29,674,000
Commercial real estate - mortgage | Substandard-accrual | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans	[1]	46,825,000
Commercial real estate - mortgage | Substandard-nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Loans		10,042,000	4,921,000
Commercial real estate - mortgage | Substandard-nonaccrual | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans		9,719,000
Commercial real estate - mortgage | Doubtful-nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Loans		74,000	0
Commercial real estate - mortgage | Doubtful-nonaccrual | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans		193,000
Consumer real estate - mortgage
Financing Receivable, Recorded Investment [Line Items]
Loans		2,552,927,000	1,185,917,000
Consumer real estate - mortgage | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans		1,334,672,000
Consumer real estate - mortgage | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans		2,449,319,000	1,160,361,000
Consumer real estate - mortgage | Pass | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans		1,247,986,000
Consumer real estate - mortgage | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans		58,928,000	1,856,000
Consumer real estate - mortgage | Special Mention | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans		58,876,000
Consumer real estate - mortgage | Substandard-accrual
Financing Receivable, Recorded Investment [Line Items]
Loans	[1]	26,116,000	15,627,000
Consumer real estate - mortgage | Substandard-accrual | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans	[1]	14,650,000
Consumer real estate - mortgage | Substandard-nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Loans		17,810,000	8,073,000
Consumer real estate - mortgage | Substandard-nonaccrual | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans		12,302,000
Consumer real estate - mortgage | Doubtful-nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Loans		754,000	0
Consumer real estate - mortgage | Doubtful-nonaccrual | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans		858,000
Construction and land development
Financing Receivable, Recorded Investment [Line Items]
Loans		1,772,799,000	912,673,000
Construction and land development | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans		728,180,000
Construction and land development | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans		1,737,057,000	897,556,000
Construction and land development | Pass | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans		699,921,000
Construction and land development | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans		12,628,000	2,716,000
Construction and land development | Special Mention | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans		9,385,000
Construction and land development | Substandard-accrual
Financing Receivable, Recorded Investment [Line Items]
Loans	[1]	19,241,000	5,788,000
Construction and land development | Substandard-accrual | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans	[1]	17,717,000
Construction and land development | Substandard-nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Loans		3,873,000	6,613,000
Construction and land development | Substandard-nonaccrual | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans		1,157,000
Construction and land development | Doubtful-nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Loans		0	0
Construction and land development | Doubtful-nonaccrual | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans		0
Commercial and industrial
Financing Receivable, Recorded Investment [Line Items]
Loans		3,688,357,000	2,891,710,000
Commercial and industrial | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans		508,885,000
Commercial and industrial | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans		3,565,754,000	2,782,713,000
Commercial and industrial | Pass | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans		489,340,000
Commercial and industrial | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans		36,759,000	25,641,000
Commercial and industrial | Special Mention | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans		7,881,000
Commercial and industrial | Substandard-accrual
Financing Receivable, Recorded Investment [Line Items]
Loans	[1]	78,637,000	75,861,000
Commercial and industrial | Substandard-accrual | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans	[1]	9,881,000
Commercial and industrial | Substandard-nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Loans		7,206,000	7,492,000
Commercial and industrial | Substandard-nonaccrual | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans		1,783,000
Commercial and industrial | Doubtful-nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Loans		1,000	3,000
Commercial and industrial | Doubtful-nonaccrual | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans		0
Consumer and other
Financing Receivable, Recorded Investment [Line Items]
Loans		357,310,000	266,129,000
Consumer and other | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans		79,845,000
Consumer and other | Pass
Financing Receivable, Recorded Investment [Line Items]
Loans		355,314,000	264,723,000
Consumer and other | Pass | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans		79,163,000
Consumer and other | Special Mention
Financing Receivable, Recorded Investment [Line Items]
Loans		1,432,000	802,000
Consumer and other | Special Mention | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans		678,000
Consumer and other | Substandard-accrual
Financing Receivable, Recorded Investment [Line Items]
Loans	[1]	108,000	129,000
Consumer and other | Substandard-accrual | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans	[1]	0
Consumer and other | Substandard-nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Loans		456,000	475,000
Consumer and other | Substandard-nonaccrual | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans		4,000
Consumer and other | Doubtful-nonaccrual
Financing Receivable, Recorded Investment [Line Items]
Loans		0	$ 0
Consumer and other | Doubtful-nonaccrual | BNC Bancorp | Historical Cost Basis
Financing Receivable, Recorded Investment [Line Items]
Loans		$ 0

[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 $182.5 million at June 30, 2017, compared to $114.6 million at December 31, 2016.