Loan-to-value (LTV) ratio for adjustable rate loans.

No definition available.

Name:	tmp_LoanToValueAdjustedRateLoans
Namespace Prefix:	tmp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Loan-to-value (LTV) ratio for fixed rate loans.

+ References

No definition available.

+ Details

Name:	tmp_LoanToValueFixedRateLoans
Namespace Prefix:	tmp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Loan-to-value (LTV) ratio for loans requiring private mortgage insurance that reduced ltv exposure.

+ References

No definition available.

+ Details

Name:	tmp_LoanToValuePrivateMortgageInsurance
Namespace Prefix:	tmp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Loans and Leases Receivable, Impaired, Commitments To Lend To Nonperforming Loans

+ References

No definition available.

+ Details

Name:	tmp_LoansandLeasesReceivableImpairedCommitmentsToLendToNonperformingLoans
Namespace Prefix:	tmp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Maximum Loan To Value

+ References

No definition available.

+ Details

Name:	tmp_MaximumLoanToValue
Namespace Prefix:	tmp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Mortgage Loans On Real Estate, Initial Rate Below The Fully Indexed Rate, Percent

+ References

No definition available.

+ Details

Name:	tmp_MortgageLoansOnRealEstateDifferenceBetweenInitialRateAndFullyIndexedRatePercent
Namespace Prefix:	tmp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Nature Of Operations, Number of Banking Offices

+ References

No definition available.

+ Details

Name:	tmp_NatureOfOperationsNumberOfBankingOffices
Namespace Prefix:	tmp_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Nature of Operations, Number of Subsidiary Banks

+ References

No definition available.

+ Details

Name:	tmp_NatureOfOperationsNumberOfSubsidiaryBanks
Namespace Prefix:	tmp_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

This is the average principal amount (during the year) of the securitized and unsecuritized financial assets.

+ References

No definition available.

+ Details

Name:	tmp_Residentialmortgageloansserviced
Namespace Prefix:	tmp_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The periodic amortization (in proportion to and over the period of estimated net servicing income or loss) of capitalized servicing rights, which contractually entitle the servicer to receive fees and ancillary revenues for performing billing, collection, disbursement and recordkeeping services in connection with a mortgage portfolio. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 4
-Subparagraph (a)(4)
-URI http://asc.fasb.org/extlink&oid=68078379&loc=d3e122739-111746

+ Details

Name:	us-gaap_AmortizationOfMortgageServicingRightsMSRs
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_BusinessAcquisitionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the collateral pledged in support of federal home loan bank advances outstanding.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6479118&loc=d3e64650-112822

+ Details

Name:	us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresCollateralPledged1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The gains (losses) included in earnings that represent the difference between the sale price and the carrying value of loans made to finance real estate acquisitions. This element refers to the gain (loss) and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.

+ References

+ Details

Name:	us-gaap_GainLossOnSaleOfMortgageLoans
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Reflects the amount of additional interest income that would have been recorded if impaired or nonperforming loans were instead current, in compliance with their original terms, and outstanding throughout the reporting period or since origination (if held for part of the period).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82895541&loc=d3e18794-111554

+ Details

Name:	us-gaap_LoansAndLeasesReceivableImpairedInterestLostOnNonaccrualLoans
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount, after allowance for bad debt, of other loan receivables held-for-sale that are not part of a disposal group. Excludes loans and leases covered under loss sharing agreements and loans classified as debt securities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

+ Details

Name:	us-gaap_LoansReceivableHeldForSaleNetNotPartOfDisposalGroupOther
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The adjustment to the carrying value of the rights retained or purchased to service mortgages. These adjustments are made when the estimate of the fair value is changed. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 4
-Subparagraph (a)(6)
-URI http://asc.fasb.org/extlink&oid=68078379&loc=d3e122739-111746

+ Details

Name:	us-gaap_MortgageServicingRightsMSRImpairmentRecovery
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash inflow from sales of loans that are secured with real estate mortgages and are held with the intention to resell in the near future.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 21
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3461-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3536-108585

+ Details

Name:	us-gaap_ProceedsFromSaleOfMortgageLoansHeldForSale
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amortized amount of contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 4
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=68078379&loc=d3e122739-111746

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122501-111745

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 25
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=7524895&loc=d3e120260-111741

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122492-111745

+ Details

Name:	us-gaap_ServicingAssetAtAmortizedValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of additions from purchases, assumption or transfer to contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer.

+ References

+ Details

Name:	us-gaap_ServicingAssetAtAmortizedValueAdditions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	srt_StatementGeographicalAxis=tmp_TompkinsCayugaCortlandandSchuylerCountiesNewYorkMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=tmp_WyomingLivingstonGenesseeOrleansandMonroeNewYorkMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=tmp_PutnamCountryDutchessCountryandWestchesterNewYorkMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=tmp_BerksMontgomeryPhiladelphiaDelewareandSchuylkillPennsylvaniaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LoanToValueAxis=us-gaap_Ltv80To100PercentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialRealEstatePortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=tmp_AgricultureLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Loans and Leases - Narrative (Details)	12 Months Ended
Loans and Leases - Narrative (Details)	Dec. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2018 USD ($) banking_office	Dec. 31, 2018 USD ($) subsidiary_bank	Dec. 31, 2018 USD ($) subsidiary_trust	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Business Acquisition [Line Items]
Initial rate below the fully indexed rate, percent (less than)		0.01%
Sale of residential mortgage loans	$ 27,700,000					$ 4,600,000	$ 3,900,000
Net gains on sale of residential mortgage loans	458,000					50,000	95,000
Mortgage servicing assets added during the period	207,000					38,000	21,000
Amortization of mortgage servicing assets	69,000					122,000	157,000
Residential mortgage loans serviced	120,900,000					104,100,000
Mortgage servicing rights, amortized cost	805,000	$ 805,000	$ 805,000	$ 805,000	$ 805,000	667,000
Mortgage servicing rights (MSR) impairment	0					0
Loans held for sale	2,700,000	2,700,000	2,700,000	2,700,000	2,700,000	280,000
Residential mortgage loans used to secure advances from FHLB	425,000,000	425,000,000	$ 425,000,000	$ 425,000,000	$ 425,000,000	475,000,000
Number of subsidiary banks			4	3	4
Interest income on nonaccrual loans	1,000,000					$ 1,000,000	$ 1,000,000
Loans and leases receivable, impaired, commitments to lend to nonperforming loans	$ 0	$ 0	$ 0	$ 0	$ 0
Tompkins, Cayuga, Cortland and Schuyler Counties, New York
Business Acquisition [Line Items]
Number of banking offices \| banking_office			14
Wyoming, Livingston, Genessee, Orleans and Monroe, New York
Business Acquisition [Line Items]
Number of banking offices \| banking_office			18
Putnam Country, Dutchess Country and Westchester, New York
Business Acquisition [Line Items]
Number of banking offices \| banking_office			14
Berks, Montgomery, Philadelphia, Deleware and Schuylkill, Pennsylvania
Business Acquisition [Line Items]
Number of banking offices \| banking_office			20
LTV 80 to 100 Percent
Business Acquisition [Line Items]
Loan to value - fixed rate loans (percent)	80.00%	80.00%	80.00%	80.00%	80.00%
Loan to value - adjusted rate loans (percent)	85.00%	85.00%	85.00%	85.00%	85.00%
Loan to value - private mortgage insurance (percent)	78.00%	78.00%	78.00%	78.00%	78.00%
Commercial real estate
Business Acquisition [Line Items]
Loan to value - debt service coverage ratio	75.00%	75.00%	75.00%	75.00%	75.00%
Agriculture \| Commercial real estate
Business Acquisition [Line Items]
Loan to value - debt service coverage ratio	75.00%	75.00%	75.00%	75.00%	75.00%