Commitments and Contingencies - Narrative (Details)	Sep. 29, 2020 retirementPlan
Commitments and Contingencies Disclosure [Abstract]
Number of retirement plans subject to class action	2

Number Of Retirement Plans Subject To Class Action

No definition available.

Name:	tnet_NumberOfRetirementPlansSubjectToClassAction
Namespace Prefix:	tnet_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant