Other Deductions, Net (Schedule Of Other Deductions, Net) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Other deductions, net [Line Items]
Amortization of intangibles	$ 60	$ 47	$ 177	$ 154
Restructuring costs	20	14	40	38
Other	(15)	16	(45)	51
Total	65	$ 77	172	243
Increase (decrease) in intangibles amortization from acquisitions			42
Higher (lower) acquisition and divestiture related costs	(7)		(42)
Change in gain (loss) from foreign currency exchange transactions			9
Change in pension expense (income)	$ (11)		$ (33)
Pentair's Valves & Controls [Member] | Order or Production Backlog [Member]
Other deductions, net [Line Items]
Backlog amortization				$ 19