CONSOLIDATED STATEMENTS OF EARNINGS (unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Revenues	$ 3,090	$ 3,073
Expenses:
Operating	1,683	1,563
Selling, general and administrative	684	739
Depreciation and amortization	50	53
Restructuring and related costs	71	0
Total expenses	2,488	2,355
Operating income	602	718
Interest expense, net	(127)	(147)
Equity in net earnings of investee companies	1	1
Loss on marketable securities	(46)	0
Gain on extinguishment of debt	18	25
Other items, net	(7)	(4)
Earnings from continuing operations before provision for income taxes	441	593
Provision for income taxes	(110)	(42)
Net earnings from continuing operations	331	551
Discontinued operations, net of tax	3	2
Net earnings (Viacom and noncontrolling interests)	334	553
Net earnings attributable to noncontrolling interests	(13)	(16)
Net earnings attributable to Viacom	321	537
Amounts attributable to Viacom:
Net earnings from continuing operations	318	535
Discontinued operations, net of tax	3	2
Net earnings attributable to Viacom	$ 321	$ 537
Basic earnings per share attributable to Viacom:
Continuing operations	$ 0.79	$ 1.33
Discontinued operations	0.01	0.00
Net earnings	0.80	1.33
Diluted earnings per share attributable to Viacom:
Continuing operations	0.79	1.33
Discontinued operations	0.01	0.00
Net earnings	$ 0.80	$ 1.33
Weighted average number of common shares outstanding:
Basic (shares)	403.1	402.5
Diluted (shares)	403.5	402.6