Balances at Other Banks (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Balances at Other Banks [Abstract]
Balances at other banks	$ 61.5	$ 41.5

Balance maintained with the Federal Reserve Bank to meet reserve requirements pursuant to Federal Banking Regulations.

No definition available.

Name:	trst_FederalReserveBankReserveRequirement
Namespace Prefix:	trst_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant