Related Party Transactions (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2018
Related Party Transaction [Line Items]
Revenues Earned From Additional Related Persons		$ 1
CBS
Consolidated Statements of Earnings
Revenues	$ 35	44
Operating expenses	36	52
Consolidated Balance Sheets [Abstract]
Accounts receivable	5		$ 7
Accounts payable	1		0
Participants’ share and residuals, current	59		58
Program obligations, current	25		38
Program obligations, noncurrent	34		32
Other liabilities	1		2
Total due to CBS and other related parties	120		130
Other Related Parties
Consolidated Statements of Earnings
Revenues	15	4
Operating expenses	3	$ 2
Consolidated Balance Sheets [Abstract]
Accounts receivable	46		43
Other assets	3		3
Total due from CBS and other related parties	49		46
Accounts payable	8		7
Participants’ share and residuals, current	1		0
Other liabilities	0		2
Total due to CBS and other related parties	$ 9		$ 9