Debt (Details) - USD ($)			3 Months Ended	6 Months Ended
	Oct. 15, 2015	Oct. 14, 2015	Mar. 25, 2016	Mar. 25, 2016	Mar. 27, 2015	Mar. 10, 2016	Sep. 25, 2015	Sep. 14, 2015	Aug. 07, 2015	Jun. 22, 2012
Debt:
Document Period End Date				Mar. 25, 2016
Debt			$ 2,559,000,000	$ 2,559,000,000			$ 3,146,000,000
Less current portion			400,000,000	400,000,000			987,000,000
Long-term debt			2,159,000,000	2,159,000,000			2,159,000,000
Debt instrument, fair value			2,615,000,000	2,615,000,000			3,291,000,000
Repayments of Debt		$ 876,000,000
Gains (Losses) on Extinguishment of Debt			(168,000,000)	(168,000,000)	$ 0
Gains (Losses) on Extinguishment of Debt, before Write off of Deferred Debt Issuance Cost			172,000,000
Write-off of unamortized debt issuance costs	$ 1,000,000
Write-off of unamortized premium	5,000,000
bank facility			4,000,000,000	$ 4,000,000,000
term of bank facility for JCI merger, years				3 years 6 months
Line of Credit Facility, Maximum Borrowing Capacity			1,500,000,000.0	$ 1,500,000,000.0		$ 1,000,000,000			$ 1,500,000,000	$ 1,000,000,000
Allowable increase to revolving credit facility			250,000,000	250,000,000
Amounts drawn under revolving credit facilities			0	$ 0			0
Description of variable interest rate basis				LIBOR
Carrying amount
Debt:
Debt instrument, fair value			2,558,000,000	$ 2,558,000,000			3,126,000,000
Commercial paper
Debt:
Less current portion			400,000,000	400,000,000			0
3.375% public notes due 2015
Debt:
Less current portion			$ 0	$ 0			$ 258,000,000
Repayments of Debt	$ 258,000,000
Debt Instrument, Interest Rate, Stated Percentage	3.375%		3.375%	3.375%			3.375%
3.75% public notes due 2018
Debt:
Debt			$ 67,000,000	$ 67,000,000			$ 67,000,000
Debt Instrument, Interest Rate, Stated Percentage			3.75%	3.75%			3.75%
8.5% public notes due 2019
Debt:
Debt Instrument, Interest Rate, Stated Percentage			8.50%	8.50%			8.50%
7.0% public notes due 2019
Debt:
Debt			$ 0	$ 0
Less current portion							$ 245,000,000	$ 242,000,000
Debt Instrument, Interest Rate, Stated Percentage			7.00%	7.00%			7.00%
6.875% public notes due 2021
Debt:
Debt			$ 0	$ 0
Less current portion							$ 465,000,000	$ 462,000,000
Debt Instrument, Interest Rate, Stated Percentage			6.875%	6.875%			6.875%
4.625% public notes due 2023
Debt:
Debt			$ 42,000,000	$ 42,000,000			$ 42,000,000
Debt Instrument, Interest Rate, Stated Percentage			4.625%	4.625%			4.625%
1.375% public notes due 2025
Debt:
Debt			$ 558,000,000	$ 558,000,000			$ 558,000,000
Debt Instrument, Interest Rate, Stated Percentage			1.375%	1.375%			1.375%
3.9% public notes due 2026 [Domain]
Debt:
Debt			$ 745,000,000	$ 745,000,000			$ 745,000,000
5.125% public notes due 2045 [Domain]
Debt:
Debt			746,000,000	746,000,000			746,000,000
Other
Debt:
Debt			$ 1,000,000	$ 1,000,000			20,000,000
Less current portion							$ 19,000,000