Financial Statements of Parent Company Guarantor - Condensed Consolidating Balance Sheet (Detail) - USD ($) $ in Millions	Sep. 26, 2015	Dec. 31, 2014	Sep. 27, 2014	Dec. 31, 2013
Current assets
Cash and cash equivalents	$ 144.9	$ 110.4	$ 156.6	$ 256.0
Accounts and notes receivable, net	1,136.5	1,205.9
Inventories	1,296.2	1,130.4
Other current assets	385.7	366.8
Assets of Disposal Group, Including Discontinued Operation, Current	0.9	80.6
Total current assets	2,964.2	2,894.1
Property, plant and equipment, net	921.4	950.0
Other assets
Goodwill	5,827.4	4,741.9
Intangibles, net	2,515.6	1,608.1
Other non-current assets	426.7	436.2
Disposal Group, Including Discontinued Operation, Assets, Noncurrent	15.6	24.9
Total other assets	8,785.3	6,811.1
Total assets	12,670.9	10,655.2
Current liabilities
Current maturities of long-term debt and short-term borrowings	3.2	6.7
Accounts payable	531.0	583.1
Employee compensation and benefits	264.6	305.5
Other current liabilities	693.9	709.1
Liabilities of Disposal Group, Including Discontinued Operation, Current	3.5	35.1
Total current liabilities	1,496.2	1,639.5
Other liabilities
Long-term debt	4,983.2	2,997.4
Pension and other post-retirement compensation and benefits	301.6	322.0
Deferred tax liabilities	827.9	528.3
Other non-current liabilities	525.6	497.7
Liabilities of Disposal Group, Including Discontinued Operation, Noncurrent	0.5	6.5
Total liabilities	8,135.0	5,991.4
Equity
Shareholders' equity attributable to Pentair plc and subsidiaries	4,535.9	4,663.8
Total equity	4,535.9	4,663.8	4,967.4	6,217.7
Total liabilities and equity	12,670.9	10,655.2
Parent Company Guarantor
Current assets
Cash and cash equivalents	0.0	0.0	0.0	0.5
Accounts and notes receivable, net	0.0	0.0
Inventories		0.0
Other current assets	1.1	0.0
Total current assets	1.1	0.0
Property, plant and equipment, net		0.0
Other assets
Investments in subsidiaries	4,981.6	4,733.0
Other non-current assets	36.9	80.2
Total other assets	5,018.5	4,813.2
Total assets	5,019.6	4,813.2
Current liabilities
Current maturities of long-term debt and short-term borrowings		0.0
Accounts payable	1.3	0.9
Employee compensation and benefits	0.3	0.2
Other current liabilities	66.1	120.6
Total current liabilities	67.7	121.7
Other liabilities
Long-term debt	402.2	11.4
Other non-current liabilities	13.8	16.3
Total liabilities	483.7	149.4
Equity
Shareholders' equity attributable to Pentair plc and subsidiaries	4,535.9
Total equity		4,663.8
Total liabilities and equity	5,019.6	4,813.2
Guarantor Subsidiary [Member]
Current assets
Cash and cash equivalents	0.0
Accounts and notes receivable, net	0.0
Other current assets	14.8	17.6
Total current assets	14.8	17.6
Other assets
Investments in subsidiaries	4,969.9	4,893.8
Other non-current assets	0.0
Total other assets	4,969.9	4,893.8
Total assets	4,984.7	4,911.4
Current liabilities
Accounts payable	0.0
Employee compensation and benefits	0.1	0.6
Other current liabilities	1.4	2.2
Total current liabilities	1.5	2.8
Other liabilities
Long-term debt	1.6	175.6
Other non-current liabilities	0.0
Total liabilities	3.1	178.4
Equity
Shareholders' equity attributable to Pentair plc and subsidiaries	4,981.6
Total equity		4,733.0
Total liabilities and equity	4,984.7	4,911.4
Subsidiary Issuer
Current assets
Cash and cash equivalents	0.2	0.1	0.2	47.0
Accounts and notes receivable, net	0.0	0.0
Inventories		0.0
Other current assets	19.7	2.0
Total current assets	19.9	2.1
Property, plant and equipment, net		0.0
Other assets
Investments in subsidiaries	9,873.3	7,612.2
Other non-current assets	1,232.6	1,381.8
Total other assets	11,105.9	8,994.0
Total assets	11,125.8	8,996.1
Current liabilities
Current maturities of long-term debt and short-term borrowings		0.0
Accounts payable	0.8	0.0
Other current liabilities	15.8	10.9
Total current liabilities	16.6	10.9
Other liabilities
Long-term debt	4,844.8	2,860.6
Deferred tax liabilities	2.9	2.9
Total liabilities	4,864.3	2,874.4
Equity
Shareholders' equity attributable to Pentair plc and subsidiaries	6,261.5
Total equity		6,121.7
Total liabilities and equity	11,125.8	8,996.1
Non-Guarantor Subsidiaries
Current assets
Cash and cash equivalents	144.7	110.3	$ 156.4	$ 208.5
Accounts and notes receivable, net	1,136.5	1,206.8
Inventories	1,296.2	1,130.4
Other current assets	391.7	367.6
Assets of Disposal Group, Including Discontinued Operation, Current	0.9	80.6
Total current assets	2,970.0	2,895.7
Property, plant and equipment, net	921.4	950.0
Other assets
Goodwill	5,827.4	4,741.9
Intangibles, net	2,515.6	1,608.1
Other non-current assets	367.5	345.0
Disposal Group, Including Discontinued Operation, Assets, Noncurrent	15.6	24.9
Total other assets	8,726.1	6,719.9
Total assets	12,617.5	10,565.6
Current liabilities
Current maturities of long-term debt and short-term borrowings	3.2	6.7
Accounts payable	528.9	583.1
Employee compensation and benefits	264.2	304.7
Other current liabilities	652.2	595.8
Liabilities of Disposal Group, Including Discontinued Operation, Current	3.5	35.1
Total current liabilities	1,452.0	1,525.4
Other liabilities
Long-term debt	944.9	1,320.6
Pension and other post-retirement compensation and benefits	301.6	322.0
Deferred tax liabilities	825.0	525.4
Other non-current liabilities	511.8	481.4
Liabilities of Disposal Group, Including Discontinued Operation, Noncurrent	0.5	6.5
Total liabilities	4,035.8	4,181.3
Equity
Shareholders' equity attributable to Pentair plc and subsidiaries	8,581.7
Total equity		6,384.3
Total liabilities and equity	12,617.5	10,565.6
Eliminations
Current assets
Accounts and notes receivable, net	0.0	(0.9)
Other current assets	(41.6)	(20.4)
Total current assets	(41.6)	(21.3)
Other assets
Investments in subsidiaries	(19,824.8)	(17,239.0)
Other non-current assets	(1,210.3)	(1,370.8)
Total other assets	(21,035.1)	(18,609.8)
Total assets	(21,076.7)	(18,631.1)
Current liabilities
Accounts payable	0.0	(0.9)
Other current liabilities	(41.6)	(20.4)
Total current liabilities	(41.6)	(21.3)
Other liabilities
Long-term debt	(1,210.3)	(1,370.8)
Other non-current liabilities	0.0	0.0
Total liabilities	(1,251.9)	(1,392.1)
Equity
Shareholders' equity attributable to Pentair plc and subsidiaries	(19,824.8)
Total equity		(17,239.0)
Total liabilities and equity	$ (21,076.7)	$ (18,631.1)