Segment and Related Information - Schedule of Segment and Related Information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Interest income	$ 63,445	$ 66,093	$ 126,644	$ 131,021
Interest expense	7,079	13,775	17,309	26,789
Net Interest Income	56,366	52,318	109,335	104,232
Provision for credit loss expense	(348)	601	15,946	1,046
Noninterest income	17,177	18,520	36,137	37,927
Noninterest expense	46,888	46,070	92,628	90,279
Income Before Income Tax Expense	27,003	24,167	36,898	50,834
Income tax expense	5,540	4,743	7,449	10,338
Net Income Attributable to Noncontrolling Interests and Tompkins Financial Corporation	21,463	19,424	29,449	40,496
Less:  Net income attributable to noncontrolling interests	32	32	69	64
Net Income Attributable to Tompkins Financial Corporation	21,431	19,392	29,380	40,432
Depreciation and amortization	2,551	2,466	5,105	4,946
Assets	7,582,056	6,654,390	7,582,056	6,654,390		$ 6,725,623
Goodwill	92,447	92,447	92,447	92,447		92,447
Other intangibles, net	5,500	7,092	5,500	7,092		6,223
Net loans and leases	5,372,203	4,815,012	5,372,203	4,815,012		4,877,658
Deposits	6,377,521	4,988,897	6,377,521	4,988,897		5,212,921
Total Equity	698,029	657,677	698,029	657,677	$ 682,597	$ 663,054	$ 647,267	$ 620,871
Operating Segments | Banking
Segment Reporting Information [Line Items]
Interest income	63,445	66,092	126,644	131,022
Interest expense	7,080	13,775	17,311	26,791
Net Interest Income	56,365	52,317	109,333	104,231
Provision for credit loss expense	(348)	601	15,946	1,046
Noninterest income	6,248	7,150	13,241	14,718
Noninterest expense	37,709	37,067	74,399	72,395
Income Before Income Tax Expense	25,252	21,799	32,229	45,508
Income tax expense	5,113	4,148	6,269	8,982
Net Income Attributable to Noncontrolling Interests and Tompkins Financial Corporation	20,139	17,651	25,960	36,526
Less:  Net income attributable to noncontrolling interests	32	32	69	64
Net Income Attributable to Tompkins Financial Corporation	20,107	17,619	25,891	36,462
Depreciation and amortization	2,484	2,400	4,969	4,813
Assets	7,528,501	6,602,541	7,528,501	6,602,541
Goodwill	64,585	64,370	64,585	64,370
Other intangibles, net	2,758	3,750	2,758	3,750
Net loans and leases	5,372,203	4,815,012	5,372,203	4,815,012
Deposits	6,391,034	5,001,210	6,391,034	5,001,210
Total Equity	643,139	605,031	643,139	605,031
Operating Segments | Insurance
Segment Reporting Information [Line Items]
Interest income	1	1	2	1
Interest expense	0	0	0	0
Net Interest Income	1	1	2	1
Provision for credit loss expense	0	0	0	0
Noninterest income	7,360	7,853	15,510	16,001
Noninterest expense	6,358	6,331	12,920	12,607
Income Before Income Tax Expense	1,003	1,523	2,592	3,395
Income tax expense	260	401	691	891
Net Income Attributable to Noncontrolling Interests and Tompkins Financial Corporation	743	1,122	1,901	2,504
Less:  Net income attributable to noncontrolling interests	0	0	0	0
Net Income Attributable to Tompkins Financial Corporation	743	1,122	1,901	2,504
Depreciation and amortization	57	56	116	112
Assets	42,215	42,163	42,215	42,163
Goodwill	19,866	19,866	19,866	19,866
Other intangibles, net	2,623	3,162	2,623	3,162
Net loans and leases	0	0	0	0
Deposits	0	0	0	0
Total Equity	31,567	32,293	31,567	32,293
Operating Segments | Wealth Management
Segment Reporting Information [Line Items]
Interest income	0	0	0	0
Interest expense	0	0	0	0
Net Interest Income	0	0	0	0
Provision for credit loss expense	0	0	0	0
Noninterest income	4,095	4,059	8,469	8,257
Noninterest expense	3,347	3,214	6,392	6,326
Income Before Income Tax Expense	748	845	2,077	1,931
Income tax expense	167	194	489	465
Net Income Attributable to Noncontrolling Interests and Tompkins Financial Corporation	581	651	1,588	1,466
Less:  Net income attributable to noncontrolling interests	0	0	0	0
Net Income Attributable to Tompkins Financial Corporation	581	651	1,588	1,466
Depreciation and amortization	10	10	20	21
Assets	25,474	22,541	25,474	22,541
Goodwill	7,996	8,211	7,996	8,211
Other intangibles, net	119	180	119	180
Net loans and leases	0	0	0	0
Deposits	0	0	0	0
Total Equity	23,323	20,353	23,323	20,353
Intercompany
Segment Reporting Information [Line Items]
Interest income	(1)	0	(2)	(2)
Interest expense	(1)	0	(2)	(2)
Net Interest Income	0	0	0	0
Provision for credit loss expense	0	0	0	0
Noninterest income	(526)	(542)	(1,083)	(1,049)
Noninterest expense	(526)	(542)	(1,083)	(1,049)
Income Before Income Tax Expense	0	0	0	0
Income tax expense	0	0	0	0
Net Income Attributable to Noncontrolling Interests and Tompkins Financial Corporation	0	0	0	0
Less:  Net income attributable to noncontrolling interests	0	0	0	0
Net Income Attributable to Tompkins Financial Corporation	0	0	0	0
Depreciation and amortization	0	0	0	0
Assets	(14,134)	(12,855)	(14,134)	(12,855)
Goodwill	0	0	0	0
Other intangibles, net	0	0	0	0
Net loans and leases	0	0	0	0
Deposits	(13,513)	(12,313)	(13,513)	(12,313)
Total Equity	$ 0	$ 0	$ 0	$ 0