Subordinated Debt and Other borrowings (Details)		3 Months Ended		12 Months Ended
		Mar. 31, 2020 USD ($) subsidiary	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Debt Instrument [Line Items]
Number of wholly owned subsidiaries | subsidiary		12
Term		30 years
Total Debt Outstanding		$ 669,658,000		$ 749,080,000
Debt issuance costs and fair value adjustments		(13,337,000)
Proceeds from Issuance of Debt				296,500,000
Models with significant unobservable market parameters (Level 3)
Debt Instrument [Line Items]
Standby letters of credit	[1]	1,400,000		$ 1,400,000
Revolving credit facility
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 75,000,000
Date Established		Apr. 25, 2019
Maturity		Apr. 24, 2020
Total Debt Outstanding	[2]	$ 0
Interest Rate (as percent)	[2]
Coupon Structure		30-day LIBOR + 1.50%
Line of credit outstanding		$ 0
Unused fee, percentage		0.30%
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)		3.64%
Coupon Structure		30-day LIBOR + 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)		2.77%
Coupon Structure		30-day LIBOR + 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)		3.10%
Coupon Structure		30-day LIBOR + 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)		3.59%
Coupon Structure		30-day LIBOR + 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)		5.25%
Coupon Structure		30-day LIBOR + 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)		4.68%
Coupon Structure		30-day LIBOR + 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)		4.23%
Coupon Structure		30-day LIBOR + 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)		3.07%
Coupon Structure		30-day LIBOR + 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)		4.33%
Coupon Structure		30-day LIBOR + 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)		2.23%
Coupon Structure		30-day LIBOR + 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)		3.50%
Coupon Structure		30-day LIBOR + 1.73%
Southcoast Capital Trust III
Debt Instrument [Line Items]
Date Established		Aug. 05, 2005
Maturity		Sep. 30, 2035
Total Debt Outstanding		$ 10,310,000
Interest Rate (as percent)		2.87%
Coupon Structure		30-day LIBOR + 1.50%
Pinnacle Bank Subordinated Notes (2015)
Debt Instrument [Line Items]
Date Established		Jul. 30, 2015
Maturity		Jul. 30, 2025
Total Debt Outstanding	[3]	$ 60,000,000
Interest Rate (as percent)	[3]	4.88%
Coupon Structure		three month LIBOR + 3.128%
Pinnacle Bank Subordinated Notes
Debt Instrument [Line Items]
Date Established		Mar. 10, 2016
Maturity		Jul. 30, 2025
Total Debt Outstanding	[3]	$ 70,000,000
Interest Rate (as percent)	[3]	4.88%
Coupon Structure		three month LIBOR + 3.128%
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		three month LIBOR + 3.884%
Pinnacle Financial Notes 2019
Debt Instrument [Line Items]
Date Established		Sep. 11, 2019
Maturity		Sep. 15, 2029
Total Debt Outstanding	[5]	$ 300,000,000
Interest Rate (as percent)	[5]	4.13%
Coupon Structure		three month LIBOR + 2.775%
Subordinated Debt Due 2023
Debt Instrument [Line Items]
Repayments of Subordinated Debt			$ 8,800,000
BNC Subordinated Notes
Debt Instrument [Line Items]
Repayments of Subordinated Debt		$ 60,000,000.0
Avenue Subordinated Notes
Debt Instrument [Line Items]
Repayments of Subordinated Debt		$ 20,000,000.0

[1] At the end of each quarter, Pinnacle Financial evaluates the inherent risks of the outstanding off-balance sheet commitments, including both commitments for unfunded loans and standby letters of credit. In making this evaluation, Pinnacle Financial utilizes credit loss expectations on funded loans from our allowance for credit losses methodology and evaluates the probability that the outstanding commitment will eventually become a funded loan. As a result, at March 31, 2020 and December 31, 2019, Pinnacle Financial included in other liabilities $16.3 million and $2.4 million, respectively, representing expected credit losses on off-balance sheet commitments, which are reflected in the estimated fair values of the related commitments. Also included in the fair values at March 31, 2020 and December 31, 2019 are unamortized fees related to these commitments of $1.4 million at both dates.

[2] Borrowing capacity on the revolving credit facility is $75.0 million. At March 31, 2020, there were no amounts outstanding under this facility. An unused fee of 0.30% is assessed on the average daily unused amount of the loan. On April 22, 2020, the facility was amended to extend the maturity date to July 24, 2020.

[3] Migrates to three month LIBOR + 3.128% beginning July 30, 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] Migrates to three month LIBOR + 2.775% beginning September 15, 2024 through the end of the term.