Pro Forma Consolidated Condensed Financial Results of Operations (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2012	Jul. 02, 2011	Jun. 30, 2012	Jul. 02, 2011
Weighted average common shares outstanding
Basic	99,047	98,333	98,856	98,190
Diluted	101,165	100,065	100,785	99,825
Business Acquisition Pro Forma Information
Business Acquisition [Line Items]
Pro forma net sales from continuing operations		953,375		1,822,224
Pro forma income from continuing operations		66,075		115,517
Pro forma net income from continuing operations attributable to Pentair, Inc.		64,650		112,599
Pro forma earnings per common share - continuing operations
Basic		0.66		1.15
Diluted		0.65		1.13
Weighted average common shares outstanding
Basic		98,333		98,190
Diluted		100,065		99,825

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