Severance Reserve Rollforward (Details) $ in Millions	3 Months Ended
Dec. 31, 2018 USD ($)
Severance Liability [Roll Forward]
Severance reserve, beginning balance	$ 195
Accruals	40
Severance payments	(63)
Severance reserve, ending balance	172
Media Networks
Severance Liability [Roll Forward]
Severance reserve, beginning balance	149
Accruals	22
Severance payments	(37)
Severance reserve, ending balance	134
Filmed Entertainment
Severance Liability [Roll Forward]
Severance reserve, beginning balance	23
Accruals	14
Severance payments	(15)
Severance reserve, ending balance	22
Corporate
Severance Liability [Roll Forward]
Severance reserve, beginning balance	23
Accruals	4
Severance payments	(11)
Severance reserve, ending balance	$ 16

Carrying amount (including both current and noncurrent portions of the accrual) as of the balance sheet date pertaining to a specified type of cost associated with exit from or disposal of business activities or restructuring pursuant to a duly authorized plan.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 5.P.4(b))
-URI http://asc.fasb.org/extlink&oid=115931487&loc=d3e140904-122747

+ Details

Name:	us-gaap_RestructuringReserve
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of increase (decrease) in the accrual for restructuring costs.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 5.P.4(b))
-URI http://asc.fasb.org/extlink&oid=115931487&loc=d3e140904-122747

+ Details

Name:	us-gaap_RestructuringReservePeriodIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

Name:	us-gaap_RestructuringReserveRollForward
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of cash paid in the period related to employee severance.

+ References

No definition available.

+ Details

Name:	viab_RestructuringReserveSettledwithCashSeverance
Namespace Prefix:	viab_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=viab_MediaNetworksMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=viab_FilmEntertainmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=viab_Corporate1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: