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, 2019		Dec. 31, 2018
Number
Outstanding, beginning balance (in shares)		176,709
Granted (in shares)		0
Exercised (in shares)		(5,200)
Forfeited (in shares)		0
Outstanding, ending balance (in shares)		171,509		176,709
Weighted-Average Exercise Price
Outstanding, beginning balance (in dollars per share)		$ 22.77
Outstanding, ending balance (in dollars per share)		$ 22.70		$ 22.77
Additional disclosures
Options exercisable (in shares)		171,509
Weighted- average exercise price of options exercisable (in dollars per share)		$ 22.70
Weighted-average contractual remaining term for options outstanding		3 years 22 days		2 years 2 months 23 days
Weighted-average contractual remaining term for options exercisable		3 years 22 days
Aggregate intrinsic value		$ 5,488	[1]	$ 4,123	[2]
Aggregate intrinsic value of options exercisable	[1]	$ 5,488
Quoted closing price of common stock (in dollars per share)		$ 54.7		$ 46.1
Number of awards used in aggregate intrinsic value (in shares)		171,509		176,709

[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 $54.70 per common share at March 31, 2019 for the 171,509 options that were in-the-money at March 31, 2019.

[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 $46.10 per common share at December 31, 2018 for the 176,709 options that were in-the-money at December 31, 2018.