Financial Statements of Parent Company Guarantor - Condensed Consolidating Statement of Operations and Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 26, 2015	Sep. 27, 2014	Sep. 26, 2015	Sep. 27, 2014
Condensed Financial Statements, Captions [Line Items]
Net sales	$ 1,552.1	$ 1,758.4	$ 4,688.3	$ 5,236.5
Cost of goods sold	1,012.0	1,133.7	3,071.8	3,401.4
Gross profit	540.1	624.7	1,616.5	1,835.1
Selling, general and administrative	330.2	328.8	958.7	1,071.0
Research and development	29.9	28.5	88.7	88.2
Operating Income (Loss)	180.0	267.4	569.1	675.9
Income (Loss) from Equity Method Investments	(0.9)	(0.3)	(2.0)	(0.9)
Gain (Loss) on Disposition of Business	0.0	0.0	0.0	(0.2)
Other (income) expense:
Net interest expense	31.3	17.1	68.1	51.1
Income before income taxes and noncontrolling interest	149.6	250.6	503.0	625.5
Provision for income taxes	34.4	58.1	115.7	148.3
Net Income (Loss) from Continuing Operations	115.2	192.5	387.3	477.2
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	0.0	(1.6)	5.6	(2.6)
Discontinued Operation, Provision for Loss (Gain) on Disposal, Net of Tax	0.0	(380.1)	(4.8)	(385.7)
Net income (loss) attributable to Pentair plc	115.2	(186.0)	376.9	94.1
Income (Loss) from Continuing Operations Attributable to Parent	115.2	192.5	387.3	477.2
Comprehensive income (loss), net of tax
Net income	115.2	(186.0)	376.9	94.1
Changes in cumulative translation adjustment	85.8	178.8	238.4	190.3
Changes in market value of derivative financial instruments	(0.7)	0.8	(1.6)	1.2
Comprehensive income (loss) attributable to Pentair plc	28.7	(364.0)	136.9	(95.0)
Parent Company Guarantor
Condensed Financial Statements, Captions [Line Items]
Selling, general and administrative	17.7	3.2	30.4	10.6
Operating Income (Loss)	(17.7)	(3.2)	(30.4)	(10.6)
Other (income) expense:
Net interest expense	0.0	0.0	0.0	0.7
Income before income taxes and noncontrolling interest	115.2	192.5	386.6	477.2
Provision for income taxes	0.0	0.0	(0.7)	0.0
Net Income (Loss) from Continuing Operations	115.2	192.5	387.3	477.2
Net income (loss) attributable to Pentair plc	115.2	(186.0)	376.9	94.1
Comprehensive income (loss), net of tax
Net income	115.2	(186.0)	376.9	94.1
Changes in cumulative translation adjustment	85.8	178.8	238.4	190.3
Changes in market value of derivative financial instruments	(0.7)	0.8	(1.6)	1.2
Comprehensive income (loss) attributable to Pentair plc	28.7	(364.0)	136.9	(95.0)
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Selling, general and administrative	0.1	1.5	0.2	4.2
Operating Income (Loss)	(0.1)	(1.5)	(0.2)	(4.2)
Other (income) expense:
Net interest expense	0.0	0.9	1.3	1.2
Income before income taxes and noncontrolling interest	132.9	195.7	417.0	488.5
Provision for income taxes	0.0		0.0	0.0
Net Income (Loss) from Continuing Operations	132.9	195.7	417.0	488.5
Net income (loss) attributable to Pentair plc	132.9	(182.8)	406.6	105.4
Comprehensive income (loss), net of tax
Net income	132.9	(182.8)	406.6	105.4
Changes in cumulative translation adjustment	85.8	178.8	238.4	190.3
Changes in market value of derivative financial instruments	(0.7)	0.8	(1.6)	1.2
Comprehensive income (loss) attributable to Pentair plc	46.4	(360.8)	166.6	(83.7)
Subsidiary Issuer
Condensed Financial Statements, Captions [Line Items]
Selling, general and administrative	1.7	0.8	3.8	6.8
Operating Income (Loss)	(1.7)	(0.8)	(3.8)	(6.8)
Other (income) expense:
Net interest expense	18.0	1.0	21.8	2.0
Income before income taxes and noncontrolling interest	128.6	204.5	403.0	475.2
Provision for income taxes	0.0	0.0	0.0	1.0
Net Income (Loss) from Continuing Operations	128.6	204.5	403.0	474.2
Net income (loss) attributable to Pentair plc	128.6	(174.0)	392.6	91.1
Comprehensive income (loss), net of tax
Net income	128.6	(174.0)	392.6	91.1
Changes in cumulative translation adjustment	85.8	178.8	238.4	190.3
Changes in market value of derivative financial instruments	(0.7)	0.8	(1.6)	1.2
Comprehensive income (loss) attributable to Pentair plc	42.1	(352.0)	152.6	(98.0)
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net sales	1,552.1	1,758.4	4,688.3	5,236.5
Cost of goods sold	1,012.0	1,133.7	3,071.8	3,401.4
Gross profit	540.1	624.7	1,616.5	1,835.1
Selling, general and administrative	310.7	323.3	924.3	1,049.4
Research and development	29.9	28.5	88.7	88.2
Operating Income (Loss)	199.5	272.9	603.5	697.5
Income (Loss) from Equity Method Investments	(0.9)	(0.3)	(2.0)	(0.9)
Gain (Loss) on Disposition of Business		0.0		(0.2)
Other (income) expense:
Net interest expense	13.3	15.2	45.0	47.2
Income before income taxes and noncontrolling interest	187.1	258.0	560.5	651.0
Provision for income taxes	34.4	58.1	116.4	147.3
Net Income (Loss) from Continuing Operations	152.7	199.9	444.1	503.7
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent	0.0	(1.6)	5.6	2.6
Discontinued Operation, Provision for Loss (Gain) on Disposal, Net of Tax	0.0		(4.8)	385.7
Net income (loss) attributable to Pentair plc	152.7	(178.6)	433.7	120.6
Comprehensive income (loss), net of tax
Net income	152.7	(178.6)	433.7	120.6
Changes in cumulative translation adjustment	85.8	178.8	238.4	190.3
Changes in market value of derivative financial instruments	(0.7)	0.8	(1.6)	1.2
Comprehensive income (loss) attributable to Pentair plc	66.2	(356.6)	193.7	(68.5)
Eliminations
Other (income) expense:
Income before income taxes and noncontrolling interest	(414.2)	600.1	(1,264.1)	1,466.4
Net Income (Loss) from Continuing Operations	(414.2)	(600.1)	(1,264.1)	(1,466.4)
Net income (loss) attributable to Pentair plc	(414.2)	535.4	(1,232.9)	(317.1)
Comprehensive income (loss), net of tax
Net income	(414.2)	535.4	(1,232.9)	317.1
Changes in cumulative translation adjustment	(257.4)	(536.4)	(715.2)	570.9
Changes in market value of derivative financial instruments	2.1	(2.4)	4.8	3.6
Comprehensive income (loss) attributable to Pentair plc	(154.7)	1,069.4	(512.9)	(250.2)
Continuing Operations [Member] | Parent Company Guarantor
Condensed Financial Statements, Captions [Line Items]
Loss (earnings) from investment in subsidiaries	(132.9)	(195.7)	(417.0)	(488.5)
Continuing Operations [Member] | Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Loss (earnings) from investment in subsidiaries	(133.0)	(198.1)	(418.5)	(493.9)
Continuing Operations [Member] | Subsidiary Issuer
Condensed Financial Statements, Captions [Line Items]
Loss (earnings) from investment in subsidiaries	(148.3)	(206.3)	(428.6)	(484.0)
Continuing Operations [Member] | Eliminations
Condensed Financial Statements, Captions [Line Items]
Loss (earnings) from investment in subsidiaries	414.2	600.1	1,264.1	1,466.4
Discontinued Operations [Member] | Parent Company Guarantor
Condensed Financial Statements, Captions [Line Items]
Loss (earnings) from investment in subsidiaries	0.0	(378.5)	(10.4)	(383.1)
Discontinued Operations [Member] | Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Loss (earnings) from investment in subsidiaries	0.0	(378.5)	(10.4)	(383.1)
Discontinued Operations [Member] | Subsidiary Issuer
Condensed Financial Statements, Captions [Line Items]
Loss (earnings) from investment in subsidiaries	0.0	(378.5)	(10.4)	(383.1)
Discontinued Operations [Member] | Eliminations
Condensed Financial Statements, Captions [Line Items]
Loss (earnings) from investment in subsidiaries	$ 0.0	$ 1,135.5	$ 31.2	$ 1,149.3