Segment and Related Information - Schedule of Segment and Related Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Interest income	$ 61,114	$ 64,316	$ 180,704	$ 190,960
Interest expense	5,016	6,063	14,723	23,372
Net Interest Income	56,098	58,253	165,981	167,588
(Credit) provision for credit loss expense	(1,232)	(218)	(6,133)	17,418
Noninterest income	20,854	18,887	59,695	55,024
Noninterest expense	50,180	46,766	142,133	137,704
Income Before Income Tax Expense	28,004	30,592	89,676	67,490
Income tax expense	6,630	6,330	19,781	13,779
Net Income Attributable to Noncontrolling Interests and Tompkins Financial Corporation	21,374	24,262	69,895	53,711
Less:  Net income attributable to noncontrolling interests	32	32	96	101
Net Income Attributable to Tompkins Financial Corporation	21,342	24,230	69,799	53,610
Depreciation and amortization	2,594	2,549	7,696	7,654
Assets	8,113,110	7,794,502	8,113,110	7,794,502		$ 7,622,171
Goodwill	92,447	92,447	92,447	92,447		92,447
Other intangibles, net	3,989	5,211	3,989	5,211		4,905
Net Loans and Leases	5,050,519	5,346,004	5,050,519	5,346,004
Deposits	7,090,898	6,601,238	7,090,898	6,601,238		6,437,752
Total Equity	722,357	713,611	722,357	713,611	$ 728,253	$ 717,689	$ 698,029	$ 663,054
Operating Segments | Banking
Segment Reporting Information [Line Items]
Interest income	61,110	64,316	180,708	190,960
Interest expense	5,020	6,064	14,737	23,375
Net Interest Income	56,090	58,252	165,971	167,585
(Credit) provision for credit loss expense	(1,232)	(218)	(6,133)	17,418
Noninterest income	6,416	5,976	19,175	19,217
Noninterest expense	40,587	37,405	113,792	110,114
Income Before Income Tax Expense	23,151	27,041	77,487	59,270
Income tax expense	5,351	5,397	16,595	11,665
Net Income Attributable to Noncontrolling Interests and Tompkins Financial Corporation	17,800	21,644	60,892	47,605
Less:  Net income attributable to noncontrolling interests	32	32	96	101
Net Income Attributable to Tompkins Financial Corporation	17,768	21,612	60,796	47,504
Depreciation and amortization	2,528	2,474	7,493	7,443
Assets	8,051,446	7,738,933	8,051,446	7,738,933
Goodwill	64,370	64,585	64,370	64,585
Other intangibles, net	1,814	2,600	1,814	2,600
Net Loans and Leases	5,050,519	5,346,004	5,050,519	5,346,004
Deposits	7,105,651	6,613,421	7,105,651	6,613,421
Total Equity	659,365	657,370	659,365	657,370
Operating Segments | Insurance
Segment Reporting Information [Line Items]
Interest income	8	1	10	3
Interest expense	0	0	0	0
Net Interest Income	8	1	10	3
(Credit) provision for credit loss expense	0	0	0	0
Noninterest income	9,950	9,023	27,531	24,533
Noninterest expense	6,846	6,559	20,044	19,479
Income Before Income Tax Expense	3,112	2,465	7,497	5,057
Income tax expense	855	670	2,057	1,362
Net Income Attributable to Noncontrolling Interests and Tompkins Financial Corporation	2,257	1,795	5,440	3,695
Less:  Net income attributable to noncontrolling interests	0	0	0	0
Net Income Attributable to Tompkins Financial Corporation	2,257	1,795	5,440	3,695
Depreciation and amortization	52	57	162	173
Assets	45,855	42,269	45,855	42,269
Goodwill	19,866	19,866	19,866	19,866
Other intangibles, net	2,102	2,507	2,102	2,507
Net Loans and Leases	0	0	0	0
Deposits	0	0	0	0
Total Equity	33,529	32,095	33,529	32,095
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
(Credit) provision for credit loss expense	0	0	0	0
Noninterest income	5,047	4,434	14,638	12,903
Noninterest expense	3,306	3,348	9,946	9,740
Income Before Income Tax Expense	1,741	1,086	4,692	3,163
Income tax expense	424	263	1,129	752
Net Income Attributable to Noncontrolling Interests and Tompkins Financial Corporation	1,317	823	3,563	2,411
Less:  Net income attributable to noncontrolling interests	0	0	0	0
Net Income Attributable to Tompkins Financial Corporation	1,317	823	3,563	2,411
Depreciation and amortization	14	18	41	38
Assets	32,257	26,956	32,257	26,956
Goodwill	8,211	7,996	8,211	7,996
Other intangibles, net	73	104	73	104
Net Loans and Leases	0	0	0	0
Deposits	0	0	0	0
Total Equity	29,463	24,146	29,463	24,146
Intercompany
Segment Reporting Information [Line Items]
Interest income	(4)	(1)	(14)	(3)
Interest expense	(4)	(1)	(14)	(3)
Net Interest Income	0	0	0	0
(Credit) provision for credit loss expense	0	0	0	0
Noninterest income	(559)	(546)	(1,649)	(1,629)
Noninterest expense	(559)	(546)	(1,649)	(1,629)
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	(16,448)	(13,656)	(16,448)	(13,656)
Goodwill	0	0	0	0
Other intangibles, net	0	0	0	0
Net Loans and Leases	0	0	0	0
Deposits	(14,753)	(12,183)	(14,753)	(12,183)
Total Equity	$ 0	$ 0	$ 0	$ 0