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Pro Forma Consolidated Condensed Financial Results of Operations (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended				12 Months Ended
	Dec. 31, 2010	Oct. 02, 2010	Jul. 03, 2010	Apr. 03, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Business Acquisition [Line Items]
Loss on disposal of discontinued operations, net of tax	$ 2,292	$ (549)	$ (593)	$ (524)		$ 626	$ 19
Weighted average common shares outstanding
Basic					98,233	98,037	97,415
Diluted					99,753	99,294	98,522
Business Acquisition Pro Forma Information
Business Acquisition [Line Items]
Pro forma net sales					3,578,462	3,329,812
Pro forma income from continuing operations					49,363	177,867
Loss on disposal of discontinued operations, net of tax						(626)
Pro forma net income from continuing operations attributable to Pentair, Inc.					45,064	$ 173,375
Pro forma earnings per common share - continuing operations
Basic					0.46	$ 1.77
Diluted					0.45	$ 1.75
Weighted average common shares outstanding
Basic					98,233	98,037
Diluted					99,753	99,294