Subordinated Debt and Other borrowings (Details)		9 Months Ended
		Sep. 30, 2018 USD ($) subsidiary	Dec. 31, 2017 USD ($)
Debt Instrument [Line Items]
Total Debt Outstanding		$ 465,487,000	$ 465,505,000
Coupon Structure		LIBOR + 3.128%
Debt issuance costs and fair value adjustments		$ (7,918,000)
Number of wholly owned subsidiaries | subsidiary		12
Term		30 years
Revolving credit facility
Debt Instrument [Line Items]
Date Established		Apr. 26, 2018
Maturity		Apr. 25, 2019
Total Debt Outstanding	[1]	$ 0
Interest Rate (as percent)	[1]	0.00%
Maximum borrowing capacity		$ 75,000,000
Pinnacle Statutory Trust I
Debt Instrument [Line Items]
Date Established		Dec. 29, 2003
Maturity		Dec. 30, 2033
Total Debt Outstanding		$ 10,310,000
Interest Rate (as percent)		5.13%
Coupon Structure		30-day LIBOR + 2.80%
Debt instrument, basis spread on variable rate (as percent)		2.80%
Pinnacle Statutory Trust II
Debt Instrument [Line Items]
Date Established		Sep. 15, 2005
Maturity		Sep. 30, 2035
Total Debt Outstanding		$ 20,619,000
Interest Rate (as percent)		3.80%
Coupon Structure		30-day LIBOR + 1.40%
Debt instrument, basis spread on variable rate (as percent)		1.40%
Pinnacle Statutory Trust III
Debt Instrument [Line Items]
Date Established		Sep. 07, 2006
Maturity		Sep. 30, 2036
Total Debt Outstanding		$ 20,619,000
Interest Rate (as percent)		4.05%
Coupon Structure		30-day LIBOR + 1.65%
Debt instrument, basis spread on variable rate (as percent)		1.65%
Pinnacle Statutory Trust IV
Debt Instrument [Line Items]
Date Established		Oct. 31, 2007
Maturity		Sep. 30, 2037
Total Debt Outstanding		$ 30,928,000
Interest Rate (as percent)		5.18%
Coupon Structure		30-day LIBOR + 2.85%
Debt instrument, basis spread on variable rate (as percent)		2.85%
BNC Capital Trust I
Debt Instrument [Line Items]
Date Established		Apr. 03, 2003
Maturity		Apr. 15, 2033
Total Debt Outstanding		$ 5,155,000
Interest Rate (as percent)		5.59%
Coupon Structure		30-day LIBOR + 3.25%
Debt instrument, basis spread on variable rate (as percent)		3.25%
BNC Capital Trust II
Debt Instrument [Line Items]
Date Established		Mar. 11, 2004
Maturity		Apr. 07, 2034
Total Debt Outstanding		$ 6,186,000
Interest Rate (as percent)		5.19%
Coupon Structure		30-day LIBOR + 2.85%
Debt instrument, basis spread on variable rate (as percent)		2.85%
BNC Capital Trust III
Debt Instrument [Line Items]
Date Established		Sep. 23, 2004
Maturity		Sep. 23, 2034
Total Debt Outstanding		$ 5,155,000
Interest Rate (as percent)		4.74%
Coupon Structure		30-day LIBOR + 2.40%
Debt instrument, basis spread on variable rate (as percent)		2.40%
BNC Capital Trust IV
Debt Instrument [Line Items]
Date Established		Sep. 27, 2006
Maturity		Dec. 31, 2036
Total Debt Outstanding		$ 7,217,000
Interest Rate (as percent)		4.10%
Coupon Structure		30-day LIBOR + 1.70%
Debt instrument, basis spread on variable rate (as percent)		1.70%
Valley Financial Trust I
Debt Instrument [Line Items]
Date Established		Jun. 26, 2003
Maturity		Jun. 26, 2033
Total Debt Outstanding		$ 4,124,000
Interest Rate (as percent)		5.47%
Coupon Structure		30-day LIBOR + 3.10%
Debt instrument, basis spread on variable rate (as percent)		3.10%
Valley Financial Trust II
Debt Instrument [Line Items]
Date Established		Sep. 26, 2005
Maturity		Dec. 15, 2035
Total Debt Outstanding		$ 7,217,000
Interest Rate (as percent)		3.82%
Coupon Structure		30-day LIBOR + 1.49%
Debt instrument, basis spread on variable rate (as percent)		1.49%
Valley Financial Trust III
Debt Instrument [Line Items]
Date Established		Dec. 15, 2006
Maturity		Jan. 30, 2037
Total Debt Outstanding		$ 5,155,000
Interest Rate (as percent)		4.07%
Coupon Structure		30-day LIBOR + 1.73%
Debt instrument, basis spread on variable rate (as percent)		1.73%
Southcoast Capital Trust III
Debt Instrument [Line Items]
Date Established		Jul. 30, 2015
Maturity		Jul. 30, 2025
Total Debt Outstanding	[2]	$ 60,000,000
Interest Rate (as percent)	[2]	4.88%
Coupon Structure		LIBOR + 3.128%
Debt instrument, basis spread on variable rate (as percent)		3.128%
Trust Preferred Securities Subject to Mandatory Redemption Twelve [Member]
Debt Instrument [Line Items]
Date Established		Aug. 05, 2005
Maturity		Sep. 30, 2035
Total Debt Outstanding		$ 10,310,000
Interest Rate (as percent)		3.90%
Coupon Structure		30-day LIBOR + 1.50%
Debt instrument, basis spread on variable rate (as percent)		1.50%
Pinnacle Bank Subordinated Notes
Debt Instrument [Line Items]
Date Established		Mar. 10, 2016
Maturity		Jul. 30, 2025
Total Debt Outstanding	[2]	$ 70,000,000
Interest Rate (as percent)	[2]	4.88%
Coupon Structure		LIBOR + 3.128%
Debt instrument, basis spread on variable rate (as percent)		3.128%
Avenue Subordinated Notes
Debt Instrument [Line Items]
Date Established		Dec. 29, 2014
Maturity		Dec. 29, 2024
Total Debt Outstanding	[3]	$ 20,000,000
Interest Rate (as percent)	[3]	6.75%
Coupon Structure		LIBOR + 4.95%
Debt instrument, basis spread on variable rate (as percent)		4.95%
Debt instrument, term of variable rate		3 months
Pinnacle Financial Subordinated Notes
Debt Instrument [Line Items]
Date Established		Nov. 16, 2016
Maturity		Nov. 16, 2026
Total Debt Outstanding	[4]	$ 120,000,000
Interest Rate (as percent)	[4]	5.25%
Coupon Structure		LIBOR + 3.884%
Debt instrument, basis spread on variable rate (as percent)		3.884%
Debt instrument, term of variable rate		3 months
Townebank Subordinated Notes
Debt Instrument [Line Items]
Date Established		Oct. 15, 2013
Maturity		Oct. 15, 2023
Total Debt Outstanding	[5]	$ 10,410,000
Interest Rate (as percent)	[5]	7.08%
Coupon Structure	[5]	30-day LIBOR + 5.50%
Debt instrument, basis spread on variable rate (as percent)	[5]	5.50%
BNC Subordinated Notes
Debt Instrument [Line Items]
Date Established		Sep. 25, 2014
Maturity		Oct. 01, 2024
Total Debt Outstanding	[6]	$ 60,000,000
Interest Rate (as percent)	[6]	5.50%
Coupon Structure		LIBOR + 3.59%
Debt instrument, basis spread on variable rate (as percent)		3.59%
Debt instrument, term of variable rate		3 months
Minimum | BNC Bancorp | BNC Subordinated Notes Assumed Due October 2023
Debt Instrument [Line Items]
Interest Rate (as percent)		5.50%
Maximum | BNC Bancorp | BNC Subordinated Notes Assumed Due October 2023
Debt Instrument [Line Items]
Interest Rate (as percent)		9.50%

[1] Borrowing capacity on the revolving credit facility is $75.0 million. At September 30, 2018, there was no outstanding balance under this facility. An unused fee of 0.35% is assessed on the average daily unused amount of the loan.

[2] Migrates to three month LIBOR + 3.128% beginning July 30, 2020 through the end of the term.

[3] Migrates to three month LIBOR + 4.95% beginning January 1, 2020 through the end of the term.

[4] Migrates to three month LIBOR + 3.884% beginning November 16, 2021 through the end of the term.

[5] Coupon structure includes a floor of 5.5% and a cap of 9.5%

[6] Migrates to three month LIBOR + 3.59% beginning October 1, 2019 through the end of the term if not redeemed on that date.