Equity method investment (Details)			12 Months Ended
	Mar. 01, 2016 USD ($) Rate shares	Feb. 01, 2015 USD ($) Rate	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2017 Rate
Schedule of Equity Method Investments [Line Items]
Payments to Acquire Businesses, Gross	$ 74,100,000	$ 75,000,000
Common stock issued in the purchase agreement (in shares) | shares	860,470
Core deposits and other intangible assets				$ 15,104,038		$ 56,710,268
Amortization of intangibles			$ 8,815,609	4,281,459	$ 1,973,953
Dividends received from equity method investment			$ 21,650,046	28,982,009	$ 7,152,000
Bankers Healthcare Group, LLC [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage			49.00%				49.00%
Additional ownership percentage | Rate	19.00%
Number of board of managers designated by bank	2
Number of board managers	5
Period of which non consent of manager approves the sale	4 years
Period of inability of members to transfer of ownership interest	5 years
Core deposits and other intangible assets				16,800,000		$ 13,400,000
Amortization of intangibles			$ 3,300,000	3,400,000
Accretion income			3,100,000	2,500,000
Accretable discount			10,300,000	13,400,000
Dividends received from equity method investment			$ 21,700,000	$ 29,000,000
Bankers Healthcare Group, LLC [Member] | Pinnacle Financial [Member]
Schedule of Equity Method Investments [Line Items]
Additional ownership percentage | Rate	8.55%
Bankers Healthcare Group, LLC [Member] | Pinnacle Bank [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage | Rate		30.00%
Additional ownership percentage | Rate	10.45%