Fair Value of Financial Instruments, Carrying Amount and Estimated Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands		Dec. 31, 2020	Dec. 31, 2019
Financial assets [Abstract]
Securities held-to-maturity, fair value		$ 1,066,531	$ 201,217
Quoted Market Prices in an Active Market (Level 1)
Financial assets [Abstract]
Securities held-to-maturity, fair value		0	0
Loans Receivable, Fair Value Disclosure		0	0
Consumer loans held-for-sale		0	0
Commercial loans held-for-sale		0	0
Financial liabilities [Abstract]
Deposits and securities sold under agreements to repurchase, fair value disclosure		0	0
Federal Home Loan Bank advances		0	0
Subordinated debt and other borrowings		0	0
Off-balance sheet instruments [Abstract]
Commitments to extend credit	[1]	0	0
Models with Significant Observable Market Parameters (Level 2)
Financial assets [Abstract]
Securities held-to-maturity, fair value		1,066,531	201,217
Loans Receivable, Fair Value Disclosure		0	0
Consumer loans held-for-sale		89,625	82,986
Commercial loans held-for-sale		31,841	17,836
Financial liabilities [Abstract]
Deposits and securities sold under agreements to repurchase, fair value disclosure		0	0
Federal Home Loan Bank advances		0	0
Subordinated debt and other borrowings		0	0
Off-balance sheet instruments [Abstract]
Commitments to extend credit	[1]	0	0
Models with Significant Unobservable Market Parameters (Level 3)
Financial assets [Abstract]
Securities held-to-maturity, fair value		0	0
Loans Receivable, Fair Value Disclosure		22,407,546	19,717,845
Consumer loans held-for-sale		0	0
Commercial loans held-for-sale		0	0
Financial liabilities [Abstract]
Deposits and securities sold under agreements to repurchase, fair value disclosure		26,929,142	19,647,392
Federal Home Loan Bank advances		1,189,035	2,078,514
Subordinated debt and other borrowings		677,521	712,220
Off-balance sheet instruments [Abstract]
Commitments to extend credit	[1]	24,887	3,786
Reported Value Measurement [Member]
Financial assets [Abstract]
Securities held-to-maturity, fair value		1,028,359	188,996
Loans Receivable, Fair Value Disclosure		22,139,451	19,693,099
Consumer loans held-for-sale		87,821	81,820
Commercial loans held-for-sale		31,200	17,585
Financial liabilities [Abstract]
Deposits and securities sold under agreements to repurchase, fair value disclosure		27,833,739	20,307,382
Federal Home Loan Bank advances		1,087,927	2,062,534
Subordinated debt and other borrowings		670,575	749,080
Off-balance sheet instruments [Abstract]
Commitments to extend credit	[1]	9,692,607	8,141,920
Estimate of Fair Value Measurement [Member]
Financial assets [Abstract]
Securities held-to-maturity, fair value	[2]	1,066,531	201,217
Loans Receivable, Fair Value Disclosure	[2]	22,407,546	19,171,845
Consumer loans held-for-sale	[2]	89,625	82,986
Commercial loans held-for-sale	[2]	31,841	17,836
Financial liabilities [Abstract]
Deposits and securities sold under agreements to repurchase, fair value disclosure	[2]	26,929,142	19,647,392
Federal Home Loan Bank advances	[2]	1,189,035	2,078,514
Subordinated debt and other borrowings	[2]	677,521	712,220
Off-balance sheet instruments [Abstract]
Commitments to extend credit	[1],[2]	$ 24,887	$ 3,786

[1] At the end of each period, 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 December 31, 2020 and 2019, Pinnacle Financial included in other liabilities $23.2 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 December 31, 2020 and 2019, are unamortized fees related to these commitments of $1.7 million and $1.4 million, respectively.

[2] 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.