Fair Value of Financial Instruments - Carrying Amount and Estimated Fair Value of Financial Instruments (Details) - USD ($)		6 Months Ended	12 Months Ended
		Jun. 30, 2018	Dec. 31, 2017
Financial assets:
Securities held-to-maturity		$ 15,259,000	$ 20,830,000
Quoted market prices in an active market (Level 1)
Financial assets:
Securities held-to-maturity		0	0
Loans, net		0	0
Consumer loans held-for-sale		0	0
Commercial loans held-for-sale		0	0
Financial liabilities:
Deposits and securities sold under agreements to repurchase		0	0
Federal Home Loan Bank advances		0	0
Subordinated debt and other borrowings		0	0
Off-balance sheet instruments:
Commitments to extend credit	[1]	0	0
Standby letters of credit	[2]	0	0
Models with significant observable market parameters (Level 2)
Financial assets:
Securities held-to-maturity		15,259,000	20,830,000
Loans, net		0	0
Consumer loans held-for-sale		109,572,000	104,986,000
Commercial loans held-for-sale		21,469,000	25,761,000
Financial liabilities:
Deposits and securities sold under agreements to repurchase		0	0
Federal Home Loan Bank advances		0	0
Subordinated debt and other borrowings		0	0
Off-balance sheet instruments:
Commitments to extend credit	[1]	0	0
Standby letters of credit	[2]	0	0
Models with significant unobservable market parameters (Level 3)
Financial assets:
Securities held-to-maturity		0	0
Loans, net		16,838,989,000	15,252,953,000
Consumer loans held-for-sale		0	0
Commercial loans held-for-sale		0	0
Financial liabilities:
Deposits and securities sold under agreements to repurchase		17,401,607,000	16,516,342,000
Federal Home Loan Bank advances		1,568,693,000	1,313,311,000
Subordinated debt and other borrowings		438,051,000	445,098,000
Off-balance sheet instruments:
Commitments to extend credit	[1]	1,767,000	2,264,000
Standby letters of credit	[2]	1,097,000	800,000
Carrying/ Notional Amount
Financial assets:
Securities held-to-maturity		15,341,000	20,762,000
Loans, net		16,967,183,000	15,565,876,000
Consumer loans held-for-sale		108,592,000	103,729,000
Commercial loans held-for-sale		21,277,000	25,456,000
Financial liabilities:
Deposits and securities sold under agreements to repurchase		17,986,157,000	16,586,964,000
Federal Home Loan Bank advances		1,581,867,000	1,319,909,000
Subordinated debt and other borrowings		465,433,000	465,505,000
Off-balance sheet instruments:
Commitments to extend credit	[1]	6,323,041,000	5,788,425,000
Standby letters of credit	[2]	175,856,000	143,684,000
Estimated Fair Value
Financial assets:
Securities held-to-maturity	[3]	15,259,000	20,830,000
Loans, net	[3]	16,838,989,000	15,252,953,000
Consumer loans held-for-sale	[3]	109,572,000	104,986,000
Commercial loans held-for-sale	[3]	21,469,000	25,761,000
Financial liabilities:
Deposits and securities sold under agreements to repurchase	[3]	17,401,607,000	16,516,342,000
Federal Home Loan Bank advances	[3]	1,568,693,000	1,313,311,000
Subordinated debt and other borrowings	[3]	438,051,000	445,098,000
Off-balance sheet instruments:
Commitments to extend credit	[1],[3]	1,767,000	2,264,000
Standby letters of credit	[2],[3]	1,097,000	800,000
Nonrecurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Gain loss on Other real estate owned		$ 15,000	$ 203,000

[1] At the end of each quarter, Pinnacle Financial evaluates the inherent risks of the outstanding off-balance sheet commitments. In making this evaluation, Pinnacle Financial evaluates the credit worthiness of the borrower, the collateral supporting the commitments and any other factors similar to those used to evaluate the inherent risks of our loan portfolio. Additionally, Pinnacle Financial evaluates the probability that the outstanding commitment will eventually become a funded loan. As a result, at June 30, 2018 and December 31, 2017, Pinnacle Financial included in other liabilities $1.8 million and $2.3 million, respectively, representing the inherent risks associated with these off-balance sheet commitments.

[2] At June 30, 2018 and December 31, 2017, the aggregate fair value of Pinnacle Financial's standby letters of credit was $1.1 million and $800,000, respectively. These amounts represent the unamortized fee associated with these standby letters of credit and are included in the consolidated balance sheets of Pinnacle Financial and are believed to approximate fair value. These fair values will decrease over time as the existing standby letters of credit approach their expiration dates.

[3] Estimated fair values are consistent with an exit-price concept. The assumptions used to estimate the fair values are intended to approximate those that a market-participant would realize in a hypothetical orderly transaction.