Basis of Presentation and Summary of Significant Accounting Policies - New Accounting Standards (Detail) - USD ($) $ in Millions		12 Months Ended
	Jan. 01, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total assets		$ 4,139.5	$ 3,806.5	$ 8,633.7
Liabilities		2,185.6	1,970.4
Net periodic benefit cost		$ 1.9	13.2	$ 24.9
Reclassification from AOCI to retained earnings	$ 215.8
Reduction in prepaid long-term asset	254.3
Deferred tax asset, income tax expense	38.5
nVent
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification from AOCI to retained earnings	$ 174.6
Effect of Change | Accounting Standards Update 2017-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net periodic benefit cost			$ 13.9