Basis of Presentation (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014 Segment Payment	Dec. 31, 2013
Basis of Presentation [Abstract]
Number of past due payments on loans classified as nonperforming	3
Non-payment period of loans moved to non-accrual status	90 days
Loan-to-value ratio applicable to additional allowance (in hundredths)	90.00%
Other real estate owned	$ 6.4	$ 8.7
Undistributed earnings	$ 37.4trst_UndistributedEarningsSubDiluted
Age under which retirees can participate in company's medical plan	65 years
Age at which company provides access to Medicare Supplemental program for retirees	65 years
Number of reportable segment	1us-gaap_NumberOfReportableSegments
Building [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	20 years
Building [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	40 years
Furniture and Equipment [Member] \| Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Furniture and Equipment [Member] \| Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	7 years

The age of retirees that the company provides access to Medicare Supplemental program.

No definition available.

Name:	trst_AgeAtWhichCompanyProvidesAccessToMedicareSupplementalProgramForRetirees
Namespace Prefix:	trst_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The age under which retirees are permitted to participate in the company's medical plan, and retirees pay all of their premiums.

+ References

No definition available.

+ Details

Name:	trst_AgeUnderWhichRetireesCanParticipateInCompanySMedicalPlan
Namespace Prefix:	trst_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The loan-to-value ratio that the company's allowance methodology also includes additional allocation percentage for during the period.

+ References

No definition available.

+ Details

Name:	trst_LoanToValueRatioApplicableToAdditionalAllowance
Namespace Prefix:	trst_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The past due period before for loans considered to be in payment default.

+ References

No definition available.

+ Details

Name:	trst_NonpaymentPeriodOfLoansMovedToNonaccrualStatus
Namespace Prefix:	trst_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of past due payments on loans classified as nonperforming.

+ References

No definition available.

+ Details

Name:	trst_NumberOfPastDuePaymentsForLoansClassifiedAsNonperforming
Namespace Prefix:	trst_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The portion of the previous two years net income of the bank subsidiary that has not been paid to the parent and may be paid to the parent in the following fiscal year for dividend distributions in accordance with federal banking regulations.

+ References

No definition available.

+ Details

Name:	trst_UndistributedEarningsSubDiluted
Namespace Prefix:	trst_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

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

- Definition

Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfReportableSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Details

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

- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Carrying amount as of the balance sheet date of land and buildings obtained through foreclosure proceedings or defeasance in full or partial satisfaction of a debt arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 45

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4437-111522

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 28

-Article 12

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph c

-Subparagraph Schedule III

-Article 5

+ Details

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

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_BuildingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_OfficeEquipmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: