Segment and Related Information - Schedule of Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information [Line Items]
Interest income	$ 59,754	$ 63,199
Interest expense	4,717	10,230
Net Interest Income	55,037	52,969
Provision (credit) for credit loss expense	(2,510)	16,294
Noninterest income	19,983	18,960
Noninterest expense	45,191	45,740
Income Before Income Tax Expense	32,339	9,895
Income tax expense	6,680	1,909
Net Income Attributable to Noncontrolling Interests and Tompkins Financial Corporation	25,659	7,986
Less: Net Income Attributable to Noncontrolling Interests	33	37
Net Income Attributable to Tompkins Financial Corporation	25,626	7,949
Depreciation and amortization	2,506	2,554
Assets	8,095,342	6,743,114	$ 7,622,171
Goodwill	92,447	92,447	92,447
Other intangibles, net	4,601	5,847	4,905
Net loans and leases	5,243,454	4,885,418
Deposits	6,946,541	5,409,363	6,437,752
Total Equity	709,936	682,597	$ 717,689	$ 663,054
Operating Segments | Banking
Segment Reporting Information [Line Items]
Interest income	59,755	63,199
Interest expense	4,718	10,231
Net Interest Income	55,037	52,968
Provision (credit) for credit loss expense	(2,510)	16,294
Noninterest income	6,318	6,992
Noninterest expense	36,009	36,689
Income Before Income Tax Expense	27,856	6,977
Income tax expense	5,515	1,157
Net Income Attributable to Noncontrolling Interests and Tompkins Financial Corporation	22,341	5,820
Less: Net Income Attributable to Noncontrolling Interests	33	37
Net Income Attributable to Tompkins Financial Corporation	22,308	5,783
Depreciation and amortization	2,436	2,485
Assets	8,038,864	6,690,574
Goodwill	64,370	64,585
Other intangibles, net	2,218	2,972
Net loans and leases	5,243,454	4,885,418
Deposits	6,961,266	5,422,258
Total Equity	650,326	627,223
Operating Segments | Insurance
Segment Reporting Information [Line Items]
Interest income	0	1
Interest expense	0	0
Net Interest Income	0	1
Provision (credit) for credit loss expense	0	0
Noninterest income	9,413	8,150
Noninterest expense	6,435	6,562
Income Before Income Tax Expense	2,978	1,589
Income tax expense	801	430
Net Income Attributable to Noncontrolling Interests and Tompkins Financial Corporation	2,177	1,159
Less: Net Income Attributable to Noncontrolling Interests	0	0
Net Income Attributable to Tompkins Financial Corporation	2,177	1,159
Depreciation and amortization	56	59
Assets	43,084	41,444
Goodwill	19,866	19,866
Other intangibles, net	2,299	2,741
Net loans and leases	0	0
Deposits	0	0
Total Equity	32,569	32,632
Operating Segments | Wealth Management
Segment Reporting Information [Line Items]
Interest income	0	0
Interest expense	0	0
Net Interest Income	0	0
Provision (credit) for credit loss expense	0	0
Noninterest income	4,782	4,374
Noninterest expense	3,277	3,045
Income Before Income Tax Expense	1,505	1,329
Income tax expense	364	322
Net Income Attributable to Noncontrolling Interests and Tompkins Financial Corporation	1,141	1,007
Less: Net Income Attributable to Noncontrolling Interests	0	0
Net Income Attributable to Tompkins Financial Corporation	1,141	1,007
Depreciation and amortization	14	10
Assets	29,091	24,562
Goodwill	8,211	7,996
Other intangibles, net	84	134
Net loans and leases	0	0
Deposits	0	0
Total Equity	27,041	22,742
Intercompany
Segment Reporting Information [Line Items]
Interest income	(1)	(1)
Interest expense	(1)	(1)
Net Interest Income	0	0
Provision (credit) for credit loss expense	0	0
Noninterest income	(530)	(556)
Noninterest expense	(530)	(556)
Income Before Income Tax Expense	0	0
Income tax expense	0	0
Net Income Attributable to Noncontrolling Interests and Tompkins Financial Corporation	0	0
Less: Net Income Attributable to Noncontrolling Interests	0	0
Net Income Attributable to Tompkins Financial Corporation	0	0
Depreciation and amortization	0	0
Assets	(15,697)	(13,466)
Goodwill	0	0
Other intangibles, net	0	0
Net loans and leases	0	0
Deposits	(14,725)	(12,895)
Total Equity	$ 0	$ 0