Other Comprehensive Income (Loss) - Details about Accumulated Other Comprehensive Income (Loss) Components (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net (loss) gain on securities transactions	$ 23,808	$ 26,361	$ 27,842	$ 26,229	$ 20,981	$ 25,917	$ 25,207	$ 23,137	$ 104,240	$ 95,242	$ 86,516
Tax benefit									(21,805)	(42,620)	(27,045)
Other operating expense									(48,303)	(42,998)	(37,234)
Net income attributable to Tompkins Financial Corporation	$ 18,911	$ 20,902	$ 22,059	$ 20,436	$ 2,457	$ 17,394	$ 16,926	$ 15,717	82,308	52,494	$ 59,340
Amount Reclassified from Accumulated Other Comprehensive Income | Unrealized gains and losses on available-for-sale securities
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net (loss) gain on securities transactions									(440)	(407)
Tax benefit									108	163
Net of tax									(332)	(244)
Amount Reclassified from Accumulated Other Comprehensive Income | Net retirement plan actuarial gain
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other operating expense									(1,719)	(1,508)
Amount Reclassified from Accumulated Other Comprehensive Income | Net retirement plan prior service credit
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other operating expense									(15)	(15)
Amount Reclassified from Accumulated Other Comprehensive Income | Employee Benefit Plans
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net (loss) gain on securities transactions									(1,734)	(1,523)
Tax benefit									425	609
Net income attributable to Tompkins Financial Corporation									$ (1,309)	$ (914)