Acquisitions and Divestitures Narrative (Details) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 30, 2017 USD ($) $ / shares	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2017 USD ($)	Apr. 28, 2017 USD ($)	Sep. 30, 2016 USD ($)
Business Acquisition [Line Items]
Goodwill	$ 5,296		$ 5,296				$ 3,909
Purchase price of business, net of cash acquired			2,991	$ 62
Revenue, net	4,039	$ 3,674	10,829	10,590
Net income (loss)	425	$ 489	1,040	$ 1,219
Pentair's Valves & Controls [Member]
Business Acquisition [Line Items]
Cash paid, net of cash acquired						$ 2,960
Cash acquired						207
Goodwill						1,373
Goodwill expected tax deductible amount	$ 0		$ 0
Intangibles						$ 988
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	15 years
Revenue, net	$ 241				$ 1,600
Net income (loss)	$ (35)
Net earnings (loss) per share | $ / shares	$ (0.05)
First year pretax acquisition accounting charges	$ (37)
First year acquisition accounting charges, after-tax	$ (26)
First year acquisition accounting charges, after-tax, per share | $ / shares	$ (0.04)
Series of Individually Immaterial Business Acquisitions [Member]
Business Acquisition [Line Items]
Number of businesses acquired			2