CONSOLIDATED STATEMENTS OF EARNINGS (unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Revenues	$ 3,237	$ 3,364	$ 9,458	$ 9,944
Expenses:
Operating	1,681	1,788	4,925	5,551
Selling, general and administrative	738	756	2,249	2,205
Depreciation and amortization	51	53	159	167
Restructuring and related costs	15	21	200	237
Total expenses	2,485	2,618	7,533	8,160
Operating income	752	746	1,925	1,784
Interest expense, net	(138)	(155)	(428)	(469)
Equity in net earnings of investee companies	2	47	5	78
Gain on sale of EPIX	0	285	0	285
Other items, net	(9)	(2)	(15)	(37)
Earnings from continuing operations before provision for income taxes	607	921	1,487	1,641
Provision for income taxes	(93)	(233)	(158)	(417)
Net earnings from continuing operations	514	688	1,329	1,224
Discontinued operations, net of tax	11	3	23	3
Net earnings (Viacom and noncontrolling interests)	525	691	1,352	1,227
Net earnings attributable to noncontrolling interests	(3)	(8)	(27)	(27)
Net earnings attributable to Viacom	522	683	1,325	1,200
Amounts attributable to Viacom:
Net earnings from continuing operations	511	680	1,302	1,197
Discontinued operations, net of tax	11	3	23	3
Net earnings attributable to Viacom	$ 522	$ 683	$ 1,325	$ 1,200
Basic earnings per share attributable to Viacom:
Continuing operations	$ 1.27	$ 1.69	$ 3.23	$ 3.00
Discontinued operations	0.03	0.01	0.06	0.01
Net earnings	1.30	1.70	3.29	3.01
Diluted earnings per share attributable to Viacom:
Continuing operations	1.27	1.69	3.23	2.99
Discontinued operations	0.02	0.01	0.06	0.01
Net earnings	$ 1.29	$ 1.70	$ 3.29	$ 3.00
Weighted average number of common shares outstanding:
Basic (shares)	402.8	402.0	402.6	399.1
Diluted (shares)	403.3	402.6	402.9	400.0
Dividends declared per share of Class A and Class B common stock	$ 0.20	$ 0.20	$ 0.60	$ 0.60