Deposits - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Banking and Thrift [Abstract]
Time deposits, greater than $250,000	$ 221.7	$ 234.3

The aggregate amount of domestic time deposit liabilities in denominations of $250,000 or more.

No definition available.

Name:	tmp_TimeGreaterThanTwoHundredFiftyThousandDollars
Namespace Prefix:	tmp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant