Stock Options and Restricted Shares - Common Stock Options (Details) - Common stock options - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		12 Months Ended
		Mar. 31, 2020		Dec. 31, 2019
Number
Outstanding, beginning balance (in shares)		119,274
Granted (in shares)		0
Exercised (in shares)		(200)
Forfeited (in shares)		0
Outstanding, ending balance (in shares)		119,074		119,274
Weighted-Average Exercise Price
Outstanding, beginning balance (in dollars per share)		$ 23.45
Outstanding, ending balance (in dollars per share)		$ 23.44		$ 23.45
Additional disclosures
Options exercisable (in shares)		119,074
Weighted- average exercise price of options exercisable (in dollars per share)		$ 23.44
Weighted-average contractual remaining term for options outstanding		2 years 7 months 6 days		2 years 10 months 6 days
Weighted-average contractual remaining term for options exercisable		2 years 7 months 6 days
Aggregate intrinsic value		$ 1,678	[1]	$ 4,837	[2]
Aggregate intrinsic value of options exercisable	[1]	$ 1,678
Quoted closing price of common stock (in dollars per share)		$ 37.54		$ 64.00
Number of awards used in aggregate intrinsic value (in shares)		119,074		119,274

[1] The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying awards and the quoted closing price of Pinnacle Financial common stock of $37.54 per common share at March 31, 2020 for the 119,074 options that were in-the-money at March 31, 2020.

[2] The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying awards and the quoted closing price of Pinnacle Financial common stock of $64.00 per common share at December 31, 2019 for the 119,274 options that were in-the-money at December 31, 2019.