Segment and Related Information - Segment Information (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	Dec. 31, 2015
Segment Reporting Information [Line Items]
Interest income	$ 65,325	$ 63,984	$ 62,143	$ 60,140	$ 59,029	$ 57,772	$ 56,342	$ 53,621	$ 251,592	$ 226,764	$ 202,739
Interest expense	12,089	10,821	9,429	7,453	7,060	6,772	6,041	5,587	39,792	25,460	22,103
Net Interest Income	53,236	53,163	52,714	52,687	51,969	51,000	50,301	48,034	211,800	201,304	180,636
Provision for loan and lease losses	2,058	272	1,045	567	2,014	402	976	769	3,942	4,161	4,321
Noninterest income									77,449	69,204	68,808
Noninterest expense									181,067	171,105	158,607
Income Before Income Tax Expense	23,808	26,361	27,842	26,229	20,981	25,917	25,207	23,137	104,240	95,242	86,516
Income Tax Expense									21,805	42,620	27,045
Net Income Attributable to Noncontrolling Interests and Tompkins Financial Corporation									82,435	52,622	59,471
Less: Net income attributable to noncontrolling interests									127	128	131
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
Depreciation and amortization									9,554	8,269	6,829
Assets	6,758,436				6,648,290				6,758,436	6,648,290	6,236,756
Goodwill	92,283				92,291				92,283	92,291	92,623
Other intangibles, net	7,628				9,263				7,628	9,263	11,349
Net loans and leases	4,790,529				4,629,349				4,790,529	4,629,349	4,222,278
Deposits	4,888,959				4,837,807				4,888,959	4,837,807	4,625,139
Total equity	620,871				576,202				620,871	576,202	549,405	$ 516,466
Banking
Segment Reporting Information [Line Items]
Goodwill	64,369				64,369				64,369	64,369	64,369
Insurance
Segment Reporting Information [Line Items]
Goodwill	19,703				19,711				19,703	19,711	20,043
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									251,592	226,764	202,739
Interest expense									39,795	25,462	22,105
Net Interest Income									211,797	201,302	180,634
Provision for loan and lease losses									3,942	4,161	4,321
Noninterest income									31,738	25,498	24,402
Noninterest expense									145,070	135,750	123,004
Income Before Income Tax Expense									94,523	86,889	77,711
Income Tax Expense									19,486	39,731	23,928
Net Income Attributable to Noncontrolling Interests and Tompkins Financial Corporation									75,037	47,158	53,783
Less: Net income attributable to noncontrolling interests									127	128	131
Net Income Attributable to Tompkins Financial Corporation									74,910	47,030	53,652
Depreciation and amortization									9,194	7,927	6,401
Assets	6,707,625				6,602,242				6,707,625	6,602,242	6,190,824
Goodwill	64,370				64,369				64,370	64,369	64,369
Other intangibles, net	4,224				5,170				4,224	5,170	6,433
Net loans and leases	4,790,529				4,629,349				4,790,529	4,629,349	4,222,278
Deposits	4,900,464				4,848,654				4,900,464	4,848,654	4,633,527
Total equity	568,988				530,386				568,988	530,386	506,411
Operating Segments | Insurance
Segment Reporting Information [Line Items]
Interest income									3	2	2
Interest expense									0	0	0
Net Interest Income									3	2	2
Provision for loan and lease losses									0	0	0
Noninterest income									29,760	29,106	29,741
Noninterest expense									25,427	24,503	24,564
Income Before Income Tax Expense									4,336	4,605	5,179
Income Tax Expense									1,092	1,705	1,906
Net Income Attributable to Noncontrolling Interests and Tompkins Financial Corporation									3,244	2,900	3,273
Less: Net income attributable to noncontrolling interests									0	0	0
Net Income Attributable to Tompkins Financial Corporation									3,244	2,900	3,273
Depreciation and amortization									230	285	353
Assets	42,088				39,599				42,088	39,599	38,988
Goodwill	19,702				19,711				19,702	19,711	20,043
Other intangibles, net	3,192				3,812				3,192	3,812	4,560
Net loans and leases	0				0				0	0	0
Deposits	0				0				0	0	0
Total equity	32,996				31,083				32,996	31,083	30,825
Operating Segments | Wealth Management
Segment Reporting Information [Line Items]
Interest income									0	0	0
Interest expense									0	0	0
Net Interest Income									0	0	0
Provision for loan and lease losses									0	0	0
Noninterest income									17,997	16,345	15,842
Noninterest expense									12,616	12,597	12,216
Income Before Income Tax Expense									5,381	3,748	3,626
Income Tax Expense									1,227	1,184	1,211
Net Income Attributable to Noncontrolling Interests and Tompkins Financial Corporation									4,154	2,564	2,415
Less: Net income attributable to noncontrolling interests									0	0	0
Net Income Attributable to Tompkins Financial Corporation									4,154	2,564	2,415
Depreciation and amortization									130	57	75
Assets	21,365				17,779				21,365	17,779	15,403
Goodwill	8,211				8,211				8,211	8,211	8,211
Other intangibles, net	212				281				212	281	356
Net loans and leases	0				0				0	0	0
Deposits	0				0				0	0	0
Total equity	18,887				14,733				18,887	14,733	12,169
Intercompany
Segment Reporting Information [Line Items]
Interest income									(3)	(2)	(2)
Interest expense									(3)	(2)	(2)
Net Interest Income									0	0	0
Provision for loan and lease losses									0	0	0
Noninterest income									(2,046)	(1,745)	(1,177)
Noninterest expense									(2,046)	(1,745)	(1,177)
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	(12,642)				(11,330)				(12,642)	(11,330)	(8,459)
Goodwill	0				0				0	0	0
Other intangibles, net	0				0				0	0	0
Net loans and leases	0				0				0	0	0
Deposits	(11,505)				(10,847)				(11,505)	(10,847)	(8,388)
Total equity	$ 0				$ 0				$ 0	$ 0	$ 0