Supplemental Guarantor Information - Condensed Consolidating Statement of Cash Flows (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating activities
Net cash provided by (used for) operating activities	$ 264.7	$ 284.6
Investing activities
Capital expenditures	(44.6)	(33.8)
Proceeds from sale of property and equipment	0.4	(0.4)
Proceeds from (payments due to) the sale of businesses, net	0.7	(12.8)
Acquisitions, net of cash acquired	(284.5)	(0.9)
Net intercompany loan activity	0.0	0.0
Payments for (Proceeds from) Other Investing Activities	(1.5)	0.0
Net cash used for investing activities of continuing operations	(329.5)	(47.9)
Net cash used for investing activities of discontinued operations	0.0	(7.1)
Net cash used for investing activities	(329.5)	(55.0)
Financing activities
Net receipts of commercial paper and revolving long-term debt	91.2	46.0
Proceeds from long-term debt	400.0	0.0
Repayments of long-term debt	(151.5)	(675.1)
Premium paid on early extinguishment of debt	0.0	(16.0)
Debt issuance costs	(6.3)	(2.0)
Cash Divested from Deconsolidation	0.0	(74.2)
Distribution of cash from nVent	0.0	993.6
Net change in advances to subsidiaries	0.0	0.0
Shares issued to employees, net of shares withheld	6.8	16.0
Repurchases of ordinary shares	(150.0)	(400.0)
Dividends paid	(92.4)	(156.7)
Net cash provided by financing activities of continuing operations	97.8	(268.4)
Change in cash held for sale	0.0	27.0
Effect of exchange rate changes on cash and cash equivalents	5.9	(9.8)
Change in cash and cash equivalents	38.9	(21.6)
Cash and cash equivalents, beginning of period	74.3	86.3
Cash and cash equivalents, end of period	113.2	64.7
Parent Company Guarantor
Operating activities
Net cash provided by (used for) operating activities	248.3	197.2
Investing activities
Capital expenditures	0.0	0.0
Proceeds from sale of property and equipment	0.0	0.0
Proceeds from (payments due to) the sale of businesses, net	0.0	0.0
Acquisitions, net of cash acquired	0.0	0.0
Net intercompany loan activity	0.0	0.0
Payments for (Proceeds from) Other Investing Activities	0.0
Net cash used for investing activities of continuing operations		0.0
Net cash used for investing activities of discontinued operations		0.0
Net cash used for investing activities	0.0	0.0
Financing activities
Net receipts of commercial paper and revolving long-term debt	0.0	0.0
Proceeds from long-term debt	0.0
Repayments of long-term debt	0.0	0.0
Premium paid on early extinguishment of debt		0.0
Debt issuance costs	0.0	0.0
Cash Divested from Deconsolidation		0.0
Distribution of cash from nVent		0.0
Net change in advances to subsidiaries	(12.7)	343.6
Shares issued to employees, net of shares withheld	6.8	16.0
Repurchases of ordinary shares	(150.0)	(400.0)
Dividends paid	(92.4)	(156.7)
Net cash provided by financing activities of continuing operations	(248.3)	(197.1)
Change in cash held for sale		0.0
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0
Change in cash and cash equivalents	0.0	0.1
Cash and cash equivalents, beginning of period	0.1	0.0
Cash and cash equivalents, end of period	0.1	0.1
Guarantor Subsidiaries
Operating activities
Net cash provided by (used for) operating activities	272.4	269.2
Investing activities
Capital expenditures	0.0	0.0
Proceeds from sale of property and equipment	0.0	0.0
Proceeds from (payments due to) the sale of businesses, net	0.0	0.0
Acquisitions, net of cash acquired	0.0	0.0
Net intercompany loan activity	(131.8)	24.9
Payments for (Proceeds from) Other Investing Activities	0.0
Net cash used for investing activities of continuing operations		24.9
Net cash used for investing activities of discontinued operations		0.0
Net cash used for investing activities	(131.8)	24.9
Financing activities
Net receipts of commercial paper and revolving long-term debt	0.0	0.0
Proceeds from long-term debt	0.0
Repayments of long-term debt	0.0	0.0
Premium paid on early extinguishment of debt		0.0
Debt issuance costs	0.0	0.0
Cash Divested from Deconsolidation		0.0
Distribution of cash from nVent		0.0
Net change in advances to subsidiaries	(140.6)	(294.1)
Shares issued to employees, net of shares withheld	0.0	0.0
Repurchases of ordinary shares	0.0	0.0
Dividends paid	0.0	0.0
Net cash provided by financing activities of continuing operations	(140.6)	(294.1)
Change in cash held for sale		0.0
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0
Change in cash and cash equivalents	0.0	0.0
Cash and cash equivalents, beginning of period	0.0	0.0
Cash and cash equivalents, end of period	0.0	0.0
Subsidiary Issuer
Operating activities
Net cash provided by (used for) operating activities	282.8	274.7
Investing activities
Capital expenditures	0.0	0.0
Proceeds from sale of property and equipment	0.0	0.0
Proceeds from (payments due to) the sale of businesses, net	0.0	0.0
Acquisitions, net of cash acquired	0.0	0.0
Net intercompany loan activity	(450.5)	(62.0)
Payments for (Proceeds from) Other Investing Activities	0.0
Net cash used for investing activities of continuing operations		(62.0)
Net cash used for investing activities of discontinued operations		0.0
Net cash used for investing activities	(450.5)	(62.0)
Financing activities
Net receipts of commercial paper and revolving long-term debt	113.8	65.0
Proceeds from long-term debt	400.0
Repayments of long-term debt	(151.5)	(675.1)
Premium paid on early extinguishment of debt		(16.0)
Debt issuance costs	(6.3)	(2.0)
Cash Divested from Deconsolidation		0.0
Distribution of cash from nVent		993.6
Net change in advances to subsidiaries	(184.7)	(563.9)
Shares issued to employees, net of shares withheld	0.0	0.0
Repurchases of ordinary shares	0.0	0.0
Dividends paid	0.0	0.0
Net cash provided by financing activities of continuing operations	171.3	(198.4)
Change in cash held for sale		0.0
Effect of exchange rate changes on cash and cash equivalents	(3.6)	(14.2)
Change in cash and cash equivalents	0.0	0.1
Cash and cash equivalents, beginning of period	0.1	0.0
Cash and cash equivalents, end of period	0.1	0.1
Non-Guarantor Subsidiaries
Operating activities
Net cash provided by (used for) operating activities	287.5	464.1
Investing activities
Capital expenditures	(44.6)	(33.8)
Proceeds from sale of property and equipment	0.4	(0.4)
Proceeds from (payments due to) the sale of businesses, net	0.7	(12.8)
Acquisitions, net of cash acquired	(284.5)	(0.9)
Net intercompany loan activity	109.9	618.7
Payments for (Proceeds from) Other Investing Activities	(1.5)
Net cash used for investing activities of continuing operations		570.8
Net cash used for investing activities of discontinued operations		(7.1)
Net cash used for investing activities	(219.6)	563.7
Financing activities
Net receipts of commercial paper and revolving long-term debt	(22.6)	(19.0)
Proceeds from long-term debt	0.0
Repayments of long-term debt	0.0	0.0
Premium paid on early extinguishment of debt		0.0
Debt issuance costs	0.0	0.0
Cash Divested from Deconsolidation		(74.2)
Distribution of cash from nVent		0.0
Net change in advances to subsidiaries	(15.9)	(987.8)
Shares issued to employees, net of shares withheld	0.0	0.0
Repurchases of ordinary shares	0.0	0.0
Dividends paid	0.0	0.0
Net cash provided by financing activities of continuing operations	(38.5)	(1,081.0)
Change in cash held for sale		27.0
Effect of exchange rate changes on cash and cash equivalents	9.5	4.4
Change in cash and cash equivalents	38.9	(21.8)
Cash and cash equivalents, beginning of period	74.1	86.3
Cash and cash equivalents, end of period	113.0	64.5
Consolidation, Eliminations
Operating activities
Net cash provided by (used for) operating activities	(826.3)	(920.6)
Investing activities
Capital expenditures	0.0	0.0
Proceeds from sale of property and equipment	0.0	0.0
Proceeds from (payments due to) the sale of businesses, net	0.0	0.0
Acquisitions, net of cash acquired	0.0	0.0
Net intercompany loan activity	472.4	(581.6)
Payments for (Proceeds from) Other Investing Activities	0.0
Net cash used for investing activities of continuing operations		(581.6)
Net cash used for investing activities of discontinued operations		0.0
Net cash used for investing activities	472.4	(581.6)
Financing activities
Net receipts of commercial paper and revolving long-term debt	0.0	0.0
Proceeds from long-term debt	0.0
Repayments of long-term debt	0.0	0.0
Premium paid on early extinguishment of debt		0.0
Debt issuance costs	0.0	0.0
Cash Divested from Deconsolidation		0.0
Distribution of cash from nVent		0.0
Net change in advances to subsidiaries	353.9	1,502.2
Shares issued to employees, net of shares withheld	0.0	0.0
Repurchases of ordinary shares	0.0	0.0
Dividends paid	0.0	0.0
Net cash provided by financing activities of continuing operations	353.9	1,502.2
Change in cash held for sale		0.0
Effect of exchange rate changes on cash and cash equivalents	0.0	0.0
Change in cash and cash equivalents	0.0	0.0
Cash and cash equivalents, beginning of period	0.0	0.0
Cash and cash equivalents, end of period	$ 0.0	$ 0.0