Regulatory Matters (Details) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended	9 Months Ended
		Jun. 30, 2020 shares	Sep. 30, 2020 USD ($) $ / shares	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Preceding period of retained earnings used in calculation of dividend payable			2 years
Retained earnings			$ 1,312,929		$ 1,184,183
Quarterly common stock dividend (in dollar per share) | $ / shares			$ 0.16
Minimum To Be Well-Capitalized Under Prompt Corrective Action Regulations
Issuance of preferred stock, net of issuance costs			$ 217,126	$ 0
Depositary Shares | shares		9,000
Pinnacle Financial
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Cash dividends paid to Pinnacle Financial by Pinnacle Bank			119,100
Actual
Total capital to risk weighted assets			3,578,436		3,159,375
Tier I capital to risk weighted assets			2,702,540		2,319,234
Common Equity Tier I capital to risk weighted assets			2,485,291		2,319,112
Tier I capital to average assets	[1]		$ 2,702,540		$ 2,319,234
Actual
Total capital to risk weighted assets (as percent)			0.142		0.132
Tier I capital to risk weighted assets (as percent)			0.107		0.097
Common Equity Tier I capital to risk weighted assets (as percent)			0.099		0.097
Tier I capital to average assets (as percent)	[1]		0.085		0.091
Minimum Capital Requirement
Total capital to risk weighted assets			$ 2,015,196		$ 1,912,885
Tier I capital to risk weighted assets			1,511,397		1,434,664
Common Equity Tier I capital			1,133,547		1,075,998
Tier I capital to average assets	[1]		$ 1,273,124		$ 1,021,836
Minimum Capital Requirement
Total capital to risk weighted assets (as percent)			0.080		0.080
Tier I capital to risk weighted assets (as percent)			0.060		0.060
Common Equity Tier I capital to risk weighted assets (as percent)			0.045		0.045
Tier I capital to average assets (as percent)	[1]		0.040		0.040
Minimum To Be Well-Capitalized Under Prompt Corrective Action Regulations
Total capital to risk weighted assets			$ 2,518,994		$ 2,391,106
Tier I capital to risk weighted assets			$ 2,015,196		$ 1,912,885
Minimum To Be Well-Capitalized Under Prompt Corrective Action Regulations
Total capital to risk weighted assets (as percent)			0.100		0.100
Tier I capital to risk weighted assets (as percent)			0.080		0.080
Pinnacle Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Retained earnings			$ 675,700
Actual
Total capital to risk weighted assets			3,146,468		$ 2,906,853
Tier I capital to risk weighted assets			2,819,572		2,679,713
Common Equity Tier I capital to risk weighted assets			2,819,450		2,679,590
Tier I capital to average assets	[1]		$ 2,819,572		$ 2,679,713
Actual
Total capital to risk weighted assets (as percent)			0.126		0.122
Tier I capital to risk weighted assets (as percent)			0.113		0.112
Common Equity Tier I capital to risk weighted assets (as percent)			0.113		0.112
Tier I capital to average assets (as percent)	[1]		0.089		0.105
Minimum Capital Requirement
Total capital to risk weighted assets			$ 2,005,334		$ 1,906,839
Tier I capital to risk weighted assets			1,504,000		1,430,129
Common Equity Tier I capital			1,128,000		1,072,597
Tier I capital to average assets	[1]		$ 1,269,171		$ 1,019,210
Minimum Capital Requirement
Total capital to risk weighted assets (as percent)			0.080		0.080
Tier I capital to risk weighted assets (as percent)			0.060		0.060
Common Equity Tier I capital to risk weighted assets (as percent)			0.045		0.045
Tier I capital to average assets (as percent)	[1]		0.040		0.040
Minimum To Be Well-Capitalized Under Prompt Corrective Action Regulations
Total capital to risk weighted assets			$ 2,506,667		$ 2,383,549
Tier I capital to risk weighted assets			2,005,334		1,906,839
Common Equity Tier I capital to risk weighted assets			1,629,333		1,549,307
Tier I capital to average assets	[1]		$ 1,586,464		$ 1,274,012
Minimum To Be Well-Capitalized Under Prompt Corrective Action Regulations
Total capital to risk weighted assets (as percent)			0.100		0.100
Tier I capital to risk weighted assets (as percent)			0.080		0.080
Common Equity Tier I capital to risk weighted assets (as percent)			0.065		0.065
Tier I capital to average assets (as percent)	[1]		0.050		0.050

[1] (*) Average assets for the above calculations were based on the most recent quarter.