Segment and Related Information - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Interest income	$ 59,029	$ 57,772	$ 56,342	$ 53,621	$ 51,936	$ 51,077	$ 50,417	$ 49,309	$ 226,764	$ 202,739	$ 188,746
Interest expense	7,060	6,772	6,041	5,587	5,562	5,760	5,510	5,271	25,460	22,103	20,365
Net interest income	51,969	51,000	50,301	48,034	46,374	45,317	44,907	44,038	201,304	180,636	168,381
Provision for loan and lease losses	2,014	402	976	769	1,706	782	978	855	4,161	4,321	2,945
Noninterest income									69,204	68,808	71,940
Noninterest expense									171,105	158,607	149,862
Income Before Income Tax Expense	20,981	25,917	25,207	23,137	21,595	22,116	21,625	21,180	95,242	86,516	87,514
Income tax expense									42,620	27,045	28,962
Net Income attributable to noncontrolling interests and Tompkins Financial Corporation									52,622	59,471	58,552
Less: Net income attributable to noncontrolling interests									128	131	131
Net Income attributable to Tompkins Financial Corporation	2,457	$ 17,394	$ 16,926	$ 15,717	15,118	$ 15,138	$ 14,833	$ 14,251	52,494	59,340	58,421
Depreciation and amortization									8,269	6,829	6,468
Assets	6,648,290				6,236,756				6,648,290	6,236,756	5,689,995
Goodwill	92,291				92,623				92,291	92,623	91,792
Other intangibles, net	9,263				11,349				9,263	11,349	12,448
Net loans and leases	4,629,349				4,222,278				4,629,349	4,222,278	3,740,038
Deposits	4,837,807				4,625,139				4,837,807	4,625,139	4,395,306
Total equity	576,202				549,405				576,202	549,405	516,466	$ 489,583
Banking
Segment Reporting Information [Line Items]
Goodwill	64,369				64,369				64,369	64,369	64,369
Insurance
Segment Reporting Information [Line Items]
Goodwill	19,711				20,043				19,711	20,043	19,212
Wealth Management
Segment Reporting Information [Line Items]
Goodwill	8,211				8,211				8,211	8,211	8,211
Operating Segments | Banking
Segment Reporting Information [Line Items]
Interest income									226,764	202,739	188,598
Interest expense									25,462	22,105	20,367
Net interest income									201,302	180,634	168,231
Provision for loan and lease losses									4,161	4,321	2,945
Noninterest income									25,498	24,402	27,096
Noninterest expense									135,750	123,004	115,706
Income Before Income Tax Expense									86,889	77,711	76,676
Income tax expense									39,731	23,928	24,923
Net Income attributable to noncontrolling interests and Tompkins Financial Corporation									47,158	53,783	51,753
Less: Net income attributable to noncontrolling interests									128	131	131
Net Income attributable to Tompkins Financial Corporation									47,030	53,652	51,622
Depreciation and amortization									7,927	6,401	5,985
Assets	6,602,242				6,190,824				6,602,242	6,190,824	5,646,459
Goodwill	64,369				64,369				64,369	64,369	64,369
Other intangibles, net	5,170				6,433				5,170	6,433	7,820
Net loans and leases	4,629,349				4,222,278				4,629,349	4,222,278	3,740,038
Deposits	4,848,654				4,633,527				4,848,654	4,633,527	4,401,896
Total equity	530,386				506,411				530,386	506,411	476,138
Operating Segments | Insurance
Segment Reporting Information [Line Items]
Interest income									2	2	2
Interest expense									0	0	0
Net interest income									2	2	2
Provision for loan and lease losses									0	0	0
Noninterest income									29,106	29,741	29,818
Noninterest expense									24,503	24,564	23,783
Income Before Income Tax Expense									4,605	5,179	6,037
Income tax expense									1,705	1,906	2,416
Net Income attributable to noncontrolling interests and Tompkins Financial Corporation									2,900	3,273	3,621
Less: Net income attributable to noncontrolling interests									0	0	0
Net Income attributable to Tompkins Financial Corporation									2,900	3,273	3,621
Depreciation and amortization									285	353	367
Assets	39,599				38,988				39,599	38,988	36,625
Goodwill	19,711				20,043				19,711	20,043	19,212
Other intangibles, net	3,812				4,560				3,812	4,560	4,187
Net loans and leases	0				0				0	0	0
Deposits	0				0				0	0	0
Total equity	31,083				30,825				31,083	30,825	28,182
Operating Segments | Wealth Management
Segment Reporting Information [Line Items]
Interest income									0	0	148
Interest expense									0	0	0
Net interest income									0	0	148
Provision for loan and lease losses									0	0	0
Noninterest income									16,345	15,842	16,037
Noninterest expense									12,597	12,216	11,384
Income Before Income Tax Expense									3,748	3,626	4,801
Income tax expense									1,184	1,211	1,623
Net Income attributable to noncontrolling interests and Tompkins Financial Corporation									2,564	2,415	3,178
Less: Net income attributable to noncontrolling interests									0	0	0
Net Income attributable to Tompkins Financial Corporation									2,564	2,415	3,178
Depreciation and amortization									57	75	116
Assets	17,779				15,403				17,779	15,403	13,951
Goodwill	8,211				8,211				8,211	8,211	8,211
Other intangibles, net	281				356				281	356	441
Net loans and leases	0				0				0	0	0
Deposits	0				0				0	0	0
Total equity	14,733				12,169				14,733	12,169	12,146
Intercompany
Segment Reporting Information [Line Items]
Interest income									(2)	(2)	(2)
Interest expense									(2)	(2)	(2)
Net interest income									0	0	0
Provision for loan and lease losses									0	0	0
Noninterest income									(1,745)	(1,177)	(1,011)
Noninterest expense									(1,745)	(1,177)	(1,011)
Income Before Income Tax Expense									0	0	0
Income tax expense									0	0	0
Net Income attributable to noncontrolling interests and Tompkins Financial Corporation									0	0	0
Less: Net income attributable to noncontrolling interests									0	0	0
Net Income attributable to Tompkins Financial Corporation									0	0	0
Depreciation and amortization									0	0	0
Assets	(11,330)				(8,459)				(11,330)	(8,459)	(7,040)
Goodwill	0				0				0	0	0
Other intangibles, net	0				0				0	0	0
Net loans and leases	0				0				0	0	0
Deposits	(10,847)				(8,388)				(10,847)	(8,388)	(6,590)
Total equity	$ 0				$ 0				$ 0	$ 0	$ 0