Earnings Per Share - Basic and Diluted Earnings Per Share (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
Mar. 29, 2014	Mar. 30, 2013
Computation Of Earnings Per Share Line Items
Net income attributable to Pentair Ltd.	$ 118.6	$ 51.7
Weighted average common shares outstanding
Basic (shares)	196.2	204.8
Dilutive impact of stock options and restricted stock units (shares)	3.5	3.4
Diluted (shares)	199.7	208.2
Earnings per common share attributable to Pentair Ltd.
Basic (USD per share)	$ 0.60	$ 0.25
Diluted (USD per share)	$ 0.59	$ 0.25
Anti-dilutive stock options excluded from the calculation of diluted earnings per share	0.5	1.0

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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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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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