Stock-based compensation - Summary of shares available for grant activity (Details) - Equity Incentive Plan 2009	6 Months Ended
Dec. 31, 2017 shares
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant [Roll Forward]
Shares available for grant (in shares)	1,899,000
Additional shares authorized (in shares)	1,666,666
Granted (in shares)	(1,752,000)
RSUs withheld for taxes in net share settlements (in shares)	256,000
Canceled (in shares)	450,000
Shares available for grant (in shares)	2,520,000

Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant [Roll Forward]

No definition available.

Name:	tnav_SharebasedCompensationArrangementbySharebasedPaymentAwardNumberofSharesAvailableforGrantRollForward
Namespace Prefix:	tnav_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of additional shares authorized for issuance under an established share-based compensation plan.

+ References

No definition available.

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Other than shares newly issued, the number of additional shares issued (for example, a stock split) or canceled (for example, to correct a share issuance), during the period under the plan.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOtherShareIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of share instruments newly issued under a share-based compensation plan.

+ References

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesIssuedInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

For net-share settlement of share-based awards when the employer settles employees' income tax withholding obligations, this element represents the number of shares the employees use to repay the employer.

+ References

No definition available.

+ Details

Name:	us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_PlanNameAxis=tnav_EquityIncentivePlan2009Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: