Condensed Parent Company Only Financial Statements - Condensed Cash Flow Statements (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating activities
Net income	$ 85,030	$ 89,264	$ 77,588
Adjustments to reconcile net income to net cash provided by operating activities
Other, net	(4,151)	(11,223)	6,218
Net Cash Provided by Operating Activities	103,340	121,177	101,387
Repayment of investments in and advances to subsidiaries
Other, net	(431)	23	489
Net Cash Used in Investing Activities	(8,444)	(583,294)	(643,719)
Financing activities
Cash dividends	(33,565)	(32,415)	(31,359)
Repurchase of common shares	(15,430)	(23,773)	(9,414)
Redemption of trust preferred debentures	0	(15,150)	(4,124)
Shares issued for dividend reinvestment plan	0	2	1,825
Shares issued for employee stock ownership plan	2,951	0	0
Net proceeds from exercise of stock options	(538)	(803)	(253)
Net Cash (Used) Provided by Financing Activities	(80,166)	136,762	792,812
Net Increase (Decrease) in Cash and Cash Equivalents	14,730	(325,355)	250,480
Cash and cash equivalents at beginning of period	63,107	388,462	137,982
Total Cash and Cash Equivalents at End of Period	77,837	63,107	388,462
Tompkins (the Parent Company)
Operating activities
Net income	85,030	89,264	77,588
Adjustments to reconcile net income to net cash provided by operating activities
Equity in undistributed earnings of subsidiaries	(30,778)	(16,780)	(24,983)
Other, net	3,561	4,126	(1,541)
Net Cash Provided by Operating Activities	57,813	76,610	51,064
Repayment of investments in and advances to subsidiaries
Repayment of investments in and advances to subsidiaries	350	0	0
Other, net	29	(76)	(100)
Net Cash Used in Investing Activities	379	(76)	(100)
Financing activities
Borrowings, net	0	0	(4,000)
Cash dividends	(33,565)	(32,415)	(31,359)
Repurchase of common shares	(15,430)	(23,773)	(9,414)
Redemption of trust preferred debentures	0	(15,150)	(4,124)
Net proceeds from restricted stock awards	(1,758)	(2,292)	(1,682)
Shares issued for dividend reinvestment plan	0	2	1,825
Shares issued for employee stock ownership plan	2,951	0	0
Net proceeds from exercise of stock options	(538)	(803)	(253)
Net Cash (Used) Provided by Financing Activities	(48,340)	(74,431)	(49,007)
Net Increase (Decrease) in Cash and Cash Equivalents	9,852	2,103	1,957
Cash and cash equivalents at beginning of period	18,691	16,588	14,631
Total Cash and Cash Equivalents at End of Period	$ 28,543	$ 18,691	$ 16,588