Earnings Per Share - Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Computation Of Earnings Per Share Line Items
Net income	$ 263.7	$ 142.8	$ 351.5	$ 250.2
Net income from continuing operations	$ 68.3	$ 132.7	$ 149.0	$ 224.5
Weighted average common shares outstanding
Basic (shares)	181.7	180.9	181.9	180.8
Dilutive impact of stock options, restricted stock units and performance share units	2.1	2.1	2.0	2.0
Diluted (shares)	183.8	183.0	183.9	182.8
Earnings per common share attributable to Pentair plc
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.37	$ 0.73	$ 0.82	$ 1.24
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	1.08	0.06	1.11	0.14
Basic (USD per share)	1.45	0.79	1.93	1.38
Income (Loss) from Continuing Operations, Per Diluted Share	0.37	0.73	0.81	1.23
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share	1.06	0.05	1.10	0.14
Diluted (USD per share)	$ 1.43	$ 0.78	$ 1.91	$ 1.37
Anti-dilutive stock options excluded from the calculation of diluted earnings per share	1.7	0.0	1.9	2.0