Organization (Details) $ in Millions	Dec. 31, 2017 USD ($)
Organization
Liquidation account balance	$ 11.0

Represents the amount kept under liquidation account in connection with the conversion and reorganization of the entity from a mutual holding company to a stock holding company.

No definition available.

Name:	tbnk_ConversionAndReorganizationMutualHoldingCompanyToStockHoldingCompanyLiquidationAccountAmount
Namespace Prefix:	tbnk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant