Fair Value of Financial Instruments, Carrying Amount and Estimated Fair Value of Financial Instruments (Details) - USD ($)		Dec. 31, 2018	Dec. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Impaired loans valuation allowance, Fair Value Disclosure		$ 4,000,000	$ 2,200,000
Financial assets [Abstract]
Securities held-to-maturity, fair value	[1]	193,131,000	20,830,000
Loans Receivable, Fair Value Disclosure	[1]	17,288,795,000	15,252,953,000
Mortgage loans held-for-sale	[1]	34,929,000	104,986,000
Loans Held-for-sale, Fair Value Disclosure	[1]	16,296,000	25,761,000
Financial liabilities [Abstract]
Deposits and securities sold under agreements to repurchase	[1]	18,337,848,000	16,516,342,000
Federal Home Loan Bank advances	[1]	1,432,003,000	1,313,311,000
Subordinated debt and other borrowings	[1]	464,616,000	445,098,000
Standby Letters of Credit
Off-balance sheet instruments [Abstract]
Standby letters of credit	[1],[2]	1,131,000	800,000
Commitments to Extend Credit
Off-balance sheet instruments [Abstract]
Commitments to extend credit	[1],[3]	1,733,000	2,264,000
Reported Value Measurement
Financial assets [Abstract]
Securities held-to-maturity, fair value		194,282,000	20,762,000
Loans Receivable, Fair Value Disclosure		17,623,974,000	15,565,876,000
Mortgage loans held-for-sale		34,196,000	103,729,000
Loans Held-for-sale, Fair Value Disclosure		15,954,000	25,456,000
Financial liabilities [Abstract]
Deposits and securities sold under agreements to repurchase		18,953,848,000	16,586,964,000
Federal Home Loan Bank advances		1,443,589,000	1,319,909,000
Subordinated debt and other borrowings		485,130,000	465,505,000
Reported Value Measurement | Standby Letters of Credit
Off-balance sheet instruments [Abstract]
Standby letters of credit	[2]	177,475,000	143,684,000
Reported Value Measurement | Commitments to Extend Credit
Off-balance sheet instruments [Abstract]
Commitments to extend credit	[3]	6,921,689,000	5,788,425,000
Estimate of Fair Value Measurement | 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
Mortgage loans held-for-sale		0	0
Loans Held-for-sale, Fair Value Disclosure		0	0
Financial liabilities [Abstract]
Deposits and securities sold under agreements to repurchase		0	0
Federal Home Loan Bank advances		0	0
Subordinated debt and other borrowings		0	0
Estimate of Fair Value Measurement | Quoted Market Prices in an Active Market (Level 1) | Standby Letters of Credit
Off-balance sheet instruments [Abstract]
Standby letters of credit	[2]	0	0
Estimate of Fair Value Measurement | Quoted Market Prices in an Active Market (Level 1) | Commitments to Extend Credit
Off-balance sheet instruments [Abstract]
Commitments to extend credit	[3]	0	0
Estimate of Fair Value Measurement | Models with Significant Observable Market Parameters (Level 2)
Financial assets [Abstract]
Securities held-to-maturity, fair value		193,131,000	20,830,000
Loans Receivable, Fair Value Disclosure		0	0
Mortgage loans held-for-sale		34,929,000	104,986,000
Loans Held-for-sale, Fair Value Disclosure		16,296,000	25,761,000
Financial liabilities [Abstract]
Deposits and securities sold under agreements to repurchase		0	0
Federal Home Loan Bank advances		0	0
Subordinated debt and other borrowings		0	0
Estimate of Fair Value Measurement | Models with Significant Observable Market Parameters (Level 2) | Standby Letters of Credit
Off-balance sheet instruments [Abstract]
Standby letters of credit	[2]	0	0
Estimate of Fair Value Measurement | Models with Significant Observable Market Parameters (Level 2) | Commitments to Extend Credit
Off-balance sheet instruments [Abstract]
Commitments to extend credit	[3]	0	0
Estimate of Fair Value Measurement | Models with Significant Unobservable Market Parameters (Level 3)
Financial assets [Abstract]
Securities held-to-maturity, fair value		0	0
Loans Receivable, Fair Value Disclosure		17,288,795,000	15,252,953,000
Mortgage loans held-for-sale		0	0
Loans Held-for-sale, Fair Value Disclosure		0	0
Financial liabilities [Abstract]
Deposits and securities sold under agreements to repurchase		18,337,848,000	16,516,342,000
Federal Home Loan Bank advances		1,432,003,000	1,313,311,000
Subordinated debt and other borrowings		464,616,000	445,098,000
Estimate of Fair Value Measurement | Models with Significant Unobservable Market Parameters (Level 3) | Standby Letters of Credit
Off-balance sheet instruments [Abstract]
Standby letters of credit	[2]	1,131,000	800,000
Estimate of Fair Value Measurement | Models with Significant Unobservable Market Parameters (Level 3) | Commitments to Extend Credit
Off-balance sheet instruments [Abstract]
Commitments to extend credit	[3]	$ 1,733,000	$ 2,264,000

[1] 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.

[2] At December 31, 2018 and 2017, the fair value of Pinnacle Financial's standby letters of credit totaled $1.1 million and $800,000, respectively. This amount represents the unamortized fee associated with these standby letters of credit, which were priced at market when issued, and is included in the consolidated balance sheet of Pinnacle Financial and is believed to approximate fair value. This fair value will decrease over time as the existing standby letters of credit approach their expiration dates.

[3] At the end of each period, 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 both December 31, 2018 and 2017, respectively, Pinnacle Financial included in other liabilities $1.7 million and $2.3 million representing the inherent risks associated with these off-balance sheet commitments.