Total Equity- Summary of Changes in Total Equity (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	$ 2,085.4
Net income	79.1	$ 75.7
Other comprehensive (loss) income	(4.6)	$ (22.4)
Accounting Standards Update [Extensible List]		us-gaap:AccountingStandardsUpdate201613Member
Ending equity	$ 2,098.0
Cash dividends per common share (USD per share)	$ 0.98	$ 0.91
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	$ 0.6	$ 0.6
Ending equity	0.6	0.6
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	4.9	0.0
Stock-based compensation	9.5	11.6
Acquisition/surrender of common shares	(14.0)	(10.4)
Directors deferred compensation	0.1	(1.2)
Ending equity	0.5	0.0
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	2,393.7	2,279.4
Net income	77.7	75.0
Acquisition/surrender of common shares	(2.7)	(34.1)
Cash dividends declared	(53.3)	(49.7)
Ending equity	2,415.4	2,269.6
Retained Earnings | Cumulative effect from adoption of CECL accounting standard (Note1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity		(1.0)
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	(329.2)	(332.9)
Other comprehensive (loss) income	(4.6)	(22.4)
Ending equity	(333.8)	(355.3)
Total Hubbell Shareholders' Equity
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	2,070.0	1,947.1
Net income	77.7	75.0
Other comprehensive (loss) income	(4.6)	(22.4)
Stock-based compensation	9.5	11.6
Acquisition/surrender of common shares	(16.7)	(44.5)
Cash dividends declared	(53.3)	(49.7)
Directors deferred compensation	0.1	(1.2)
Ending equity	2,082.7	1,914.9
Total Hubbell Shareholders' Equity | Cumulative effect from adoption of CECL accounting standard (Note1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity		(1.0)
Non- controlling interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	15.4	13.4
Net income	1.4	0.7
Dividends to noncontrolling interest	(1.5)	(0.5)
Ending equity	$ 15.3	$ 13.6