Selected Quarterly Data - Quarterly Financial Information (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2013		Sep. 28, 2013		Jun. 29, 2013		Mar. 30, 2013		Dec. 31, 2012		Sep. 29, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Quarterly Financial Information [Line Items]
Net sales	$ 1,916.7		$ 1,824.8		$ 1,963.7		$ 1,774.5		$ 1,750.9		$ 865.5		$ 941.5		$ 858.2		$ 7,479.7		$ 4,416.1		$ 3,456.7
Gross profit	644.1		637.6		667.4		523.8		398.7		278.1		312.1		280.7		2,472.9		1,269.6		1,073.7
Operating income (loss)	233.8		240.0		225.9		74.3		(304.1)		55.2		119.3		86.5		774.0		(43.1)		100.2
Net income (loss) before noncontrolling interest	159.7		174.2		155.4		53.3		(274.7)		32.6		74.4		63.1		542.6		(104.6)		(3.2)
Net income (loss) attributable to Pentair Ltd.	$ 158.2		$ 172.8		$ 154.1		$ 51.7		$ (273.1)		$ 31.4		$ 72.8		$ 61.7		$ 536.8		$ (107.2)		$ (7.5)
Earnings (loss) per common share attributable to Pentair Ltd.
Basic	$ 0.80	[1]	$ 0.87	[1]	$ 0.76	[1]	$ 0.25	[1]	$ (1.31)	[1]	$ 0.31	[1]	$ 0.73	[1]	$ 0.63	[1]	$ 2.67	[1]	$ (0.84)	[1]	$ (0.08)
Diluted	$ 0.78	[1]	$ 0.85	[1]	$ 0.75	[1]	$ 0.25	[1]	$ (1.31)	[1]	$ 0.31	[1]	$ 0.72	[1]	$ 0.62	[1]	$ 2.62	[1]	$ (0.84)	[1]	$ (0.08)

[1] Amounts may not total to annual earnings because each quarter and year are calculated separately based on basic and diluted weighted-average common shares outstanding during that period