Financial Statements of Parent Company Guarantor - Condensed Consolidating Statement of Operations and Comprehensive Income (Loss) (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended					6 Months Ended
	Jun. 28, 2014	Mar. 29, 2014	Sep. 28, 2013	Jun. 29, 2013	Mar. 30, 2013	Jun. 28, 2014	Jun. 29, 2013
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 1,910.8			$ 1,963.7		$ 3,636.0	$ 3,738.2
Cost of goods sold	1,251.9			1,296.3		2,398.8	2,547.0
Gross profit	658.9			667.4		1,237.2	1,191.2
Selling, general and administrative	400.3			409.4		768.7	825.4
Research and development	30.9			32.1		60.9	65.6
Operating income (loss)	227.7			225.9		407.6	300.2
Income (Loss) from Equity Method Investments	(0.4)			(0.9)		(0.8)	(1.1)
Other (income) expense:
Loss (gain) on sale of businesses	0.2	8.0	(0.1)	0	(16.7)	8.2	(16.7)
Net interest expense	17.5			18.4		33.2	35.4
Income before income taxes and noncontrolling interest	(210.4)			(208.4)		(367.0)	(282.6)
Provision for income taxes	48.9			53.0		86.9	73.9
Noncontrolling interest	0			1.3		0	2.9
Net income (loss) attributable to Pentair Ltd.	161.5			154.1		280.1	205.8
Comprehensive income, net of tax
Net income	(161.5)			(155.4)		(280.1)	(208.7)
Changes in cumulative translation adjustment	(16.4)			41.3		11.5	118.2
Changes in market value of derivative financial instruments	(0.2)			0.4		(0.4)	(0.3)
Total comprehensive income (loss)	(178.1)			(113.7)		(269.0)	(90.8)
Less: Comprehensive income attributable to noncontrolling interest	0			(1.7)		0	(2.4)
Comprehensive income (loss) attributable to Pentair Ltd.	(178.1)			(112.0)		(269.0)	(88.4)
Parent Company Guarantor
Condensed Financial Statements, Captions [Line Items]
Selling, general and administrative	8.2			0.3		7.9	(0.7)
Operating income (loss)	(8.2)			(0.3)		(7.9)	0.7
Loss (earnings) from investment in subsidiaries	(170.1)			(157.1)		(288.7)	(207.8)
Other (income) expense:
Net interest expense	0.4			2.7		0.7	3.0
Income before income taxes and noncontrolling interest	(161.5)			(154.1)		(280.1)	(205.5)
Provision for income taxes	0			0		0	(0.3)
Net income (loss) attributable to Pentair Ltd.	161.5			154.1		280.1	205.8
Comprehensive income, net of tax
Net income	(161.5)			(154.1)		(280.1)	(205.8)
Changes in cumulative translation adjustment	(16.4)			41.7		11.5	117.7
Changes in market value of derivative financial instruments	(0.2)			0.4		(0.4)	(0.3)
Total comprehensive income (loss)				(112.0)			(88.4)
Less: Comprehensive income attributable to noncontrolling interest				0			0
Comprehensive income (loss) attributable to Pentair Ltd.	(178.1)			(112.0)		(269.0)	(88.4)
Guarantor Subsidiary [Member]
Condensed Financial Statements, Captions [Line Items]
Selling, general and administrative	2.8					2.8
Operating income (loss)	(2.8)					(2.8)
Loss (earnings) from investment in subsidiaries	(173.2)					(173.2)
Other (income) expense:
Net interest expense	0.3					0.3
Income before income taxes and noncontrolling interest	(170.1)					(170.1)
Provision for income taxes	0					0
Net income (loss) attributable to Pentair Ltd.	170.1					170.1
Comprehensive income, net of tax
Net income	(170.1)					(170.1)
Changes in cumulative translation adjustment	(16.4)					11.5
Changes in market value of derivative financial instruments	(0.2)					(0.4)
Comprehensive income (loss) attributable to Pentair Ltd.	(186.7)					(159.0)
Subsidiary Issuer
Condensed Financial Statements, Captions [Line Items]
Selling, general and administrative	2.6			3.4		5.9	7.0
Operating income (loss)	(2.6)			(3.4)		(5.9)	(7.0)
Loss (earnings) from investment in subsidiaries	(146.5)			(164.1)		(273.6)	(219.0)
Other (income) expense:
Net interest expense	0.1			3.5		1.0	6.1
Income before income taxes and noncontrolling interest	(143.8)			(157.2)		(266.7)	(205.9)
Provision for income taxes	1.0			0		1.0	0
Net income (loss) attributable to Pentair Ltd.	142.8			157.2		265.7	205.9
Comprehensive income, net of tax
Net income	(142.8)			(157.2)		(265.7)	(205.9)
Changes in cumulative translation adjustment	(16.4)			41.7		11.5	117.7
Changes in market value of derivative financial instruments	(0.2)			0.4		(0.4)	(0.3)
Total comprehensive income (loss)				(115.1)			(88.5)
Less: Comprehensive income attributable to noncontrolling interest				0			0
Comprehensive income (loss) attributable to Pentair Ltd.	(159.4)			(115.1)		(254.6)	(88.5)
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net sales	1,910.8			1,963.7		3,636.0	3,738.2
Cost of goods sold	1,251.9			1,296.3		2,398.8	2,547.0
Gross profit	658.9			667.4		1,237.2	1,191.2
Selling, general and administrative	386.7			405.7		752.1	819.1
Research and development	30.9			32.1		60.9	65.6
Operating income (loss)	241.3			229.6		424.2	306.5
Income (Loss) from Equity Method Investments	(0.4)			(0.9)		(0.8)	(1.1)
Other (income) expense:
Loss (gain) on sale of businesses	0.2			0		8.2	(16.7)
Net interest expense	16.7			12.2		31.2	26.3
Income before income taxes and noncontrolling interest	(224.8)			(218.3)		(385.6)	(298.0)
Provision for income taxes	47.9			53.0		85.9	74.2
Noncontrolling interest				1.3			2.9
Net income (loss) attributable to Pentair Ltd.	176.9			164.0		299.7	220.9
Comprehensive income, net of tax
Net income	(176.9)			(165.3)		(299.7)	(223.8)
Changes in cumulative translation adjustment	(16.4)			41.3		11.5	118.2
Changes in market value of derivative financial instruments	(0.2)			0.4		(0.4)	(0.3)
Total comprehensive income (loss)				(123.6)			(105.9)
Less: Comprehensive income attributable to noncontrolling interest				(1.7)			(2.4)
Comprehensive income (loss) attributable to Pentair Ltd.	(193.5)			(121.9)		(288.6)	(103.5)
Eliminations
Condensed Financial Statements, Captions [Line Items]
Loss (earnings) from investment in subsidiaries	489.8			321.2		735.5	426.8
Other (income) expense:
Income before income taxes and noncontrolling interest	489.8			(321.2)		735.5	(426.8)
Net income (loss) attributable to Pentair Ltd.	(489.8)			(321.2)		(735.5)	(426.8)
Comprehensive income, net of tax
Net income	489.8			(321.2)		735.5	(426.8)
Changes in cumulative translation adjustment	49.2			83.4		(34.5)	235.4
Changes in market value of derivative financial instruments	0.6			0.8		1.2	(0.6)
Total comprehensive income (loss)				(237.0)			(192.0)
Less: Comprehensive income attributable to noncontrolling interest				0			0
Comprehensive income (loss) attributable to Pentair Ltd.	$ 539.6			$ (237.0)		$ 702.2	$ (192.0)