Fair Value of Financial Instruments - Carrying Amount and Estimated Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands		Mar. 31, 2021	Dec. 31, 2020
Financial assets:
Securities Purchased under Agreements to Resell		$ 450,000	$ 0
Securities held-to-maturity		1,033,749	1,066,531
Quoted market prices in an active market (Level 1)
Financial assets:
Securities Purchased under Agreements to Resell		0
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
Models with significant observable market parameters (Level 2)
Financial assets:
Securities Purchased under Agreements to Resell		0
Securities held-to-maturity		1,033,749	1,066,531
Loans, net		0	0
Consumer loans held-for-sale		86,403	89,625
Commercial loans held-for-sale		12,634	31,841
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
Models with significant unobservable market parameters (Level 3)
Financial assets:
Securities Purchased under Agreements to Resell		433,935
Securities held-to-maturity		0	0
Loans, net		22,808,139	22,407,546
Consumer loans held-for-sale		0	0
Commercial loans held-for-sale		0	0
Financial liabilities:
Deposits and securities sold under agreements to repurchase		27,539,943	26,929,142
Federal Home Loan Bank advances		928,035	1,189,035
Subordinated debt and other borrowings		661,693	677,521
Off-balance sheet instruments:
Commitments to extend credit	[1]	25,019	24,887
Carrying/ Notional Amount
Financial assets:
Securities Purchased under Agreements to Resell		450,000
Securities held-to-maturity		1,014,345	1,028,359
Loans, net		22,805,820	22,139,451
Consumer loans held-for-sale		85,769	87,821
Commercial loans held-for-sale		12,541	31,200
Financial liabilities:
Deposits and securities sold under agreements to repurchase		28,465,057	27,833,739
Federal Home Loan Bank advances		888,115	1,087,927
Subordinated debt and other borrowings		671,002	670,575
Off-balance sheet instruments:
Commitments to extend credit	[1]	10,422,083	9,692,607
Estimated Fair Value
Financial assets:
Securities Purchased under Agreements to Resell	[2]	433,935
Securities held-to-maturity	[2]	1,033,749	1,066,531
Loans, net	[2]	22,808,139	22,407,546
Consumer loans held-for-sale	[2]	86,403	89,625
Commercial loans held-for-sale	[2]	12,634	31,841
Financial liabilities:
Deposits and securities sold under agreements to repurchase	[2]	27,539,943	26,929,142
Federal Home Loan Bank advances	[2]	928,035	1,189,035
Subordinated debt and other borrowings	[2]	661,693	677,521
Off-balance sheet instruments:
Commitments to extend credit	[1],[2]	$ 25,019	$ 24,887

[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, 2021 and December 31, 2020, Pinnacle Financial included in other liabilities $23.2 million, 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, 2021 and December 31, 2020 are unamortized fees related to these commitments of $1.8 million and $1.7 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.