Earnings Per Share - Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Computation Of Earnings Per Share Line Items
Net income	$ 87.8	$ 107.4
Income (Loss) from Continuing Operations Attributable to Parent	$ 80.7	$ 91.8
Weighted average common shares outstanding
Basic (shares)	182.0	180.7
Dilutive impact of stock options and restricted stock units (shares)	2.0	1.7
Diluted (shares)	184.0	182.4
Earnings per common share attributable to Pentair plc
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.44	$ 0.50
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Basic Share	0.04	0.09
Basic (USD per share)	0.48	0.59
Income (Loss) from Continuing Operations, Per Diluted Share	0.44	0.50
Income (Loss) from Discontinued Operations and Disposal of Discontinued Operations, Net of Tax, Per Diluted Share	0.04	0.09
Diluted (USD per share)	$ 0.48	$ 0.59
Anti-dilutive stock options excluded from the calculation of diluted earnings per share	1.8	3.1

Computation Of Earnings Per Share Line Items

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Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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Amount after tax of income (loss) from continuing operations attributable to the parent.

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The amount of net income (loss) from continuing operations per each share of common stock or unit outstanding during the reporting period.

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