Total Equity (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity		$ 1,798.9			$ 1,798.9
Net income	$ 97.9		$ 102.4		171.7	$ 162.2
Other comprehensive (loss) income					6.0
Reclassification of stranded tax effects		$ (30.0)			$ (30.0)
Cash dividends per common share (USD per share)	$ 0.84	$ 0.84	$ 0.77	$ 0.77	$ 1.68	$ 1.54
Ending equity	$ 1,855.0				$ 1,855.0
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	0.6	$ 0.6	$ 0.6	$ 0.6	0.6	$ 0.6
Ending equity	0.6	0.6	0.6	0.6	0.6	0.6
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	0.2	1.3	10.1	11.0	1.3	11.0
Stock-based compensation	4.2	4.1	4.4	5.1
Acquisition/surrender of common shares	3.5	5.3	11.9	6.1
Director's deferred compensation	0.3	0.1	0.2	0.1
Ending equity	1.2	0.2	2.8	10.1	1.2	2.8
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	2,114.7	2,064.4	1,909.0	1,892.4	2,064.4	1,892.4
Net income	96.0	72.3	100.3	58.3
Reclassification of stranded tax effects		30.0
Acquisition/surrender of common shares	20.9	6.3		0.0
ASC 606 adoption to retained earnings				0.6
Cash dividends declared	(46.0)	(45.7)	(42.3)	(42.3)
Ending equity	2,143.8	2,114.7	1,967.0	1,909.0	2,143.8	1,967.0
Purchase price of repurchased shares allocated to retained earnings					(27.2)
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	(307.4)	(285.7)	(257.7)	(269.8)	(285.7)	(269.8)
Other comprehensive (loss) income	(2.3)	8.3	(27.8)	12.1
Reclassification of stranded tax effects		(30.0)
Ending equity	(309.7)	(307.4)	(285.5)	(257.7)	(309.7)	(285.5)
Total Hubbell Shareholders' Equity
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	1,808.1	1,780.6	1,662.0	1,634.2	1,780.6	1,634.2
Net income	96.0	72.3	100.3	58.3
Other comprehensive (loss) income	(2.3)	8.3	(27.8)	12.1
Stock-based compensation	4.2	4.1	4.4	5.1
Acquisition/surrender of common shares	24.4	11.6	11.9	6.1
ASC 606 adoption to retained earnings				0.6
Cash dividends declared	(46.0)	(45.7)	(42.3)	(42.3)
Director's deferred compensation	0.3	0.1	0.2	0.1
Ending equity	1,835.9	1,808.1	1,684.9	1,662.0	1,835.9	1,684.9
Non- controlling interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	18.8	18.3	16.5	13.7	18.3	13.7
Net income	1.9	1.5	2.1	1.5
Dividends to noncontrolling interest	(1.6)	(1.0)	(1.7)	(1.1)
Aclara noncontrolling interest				2.4
Ending equity	$ 19.1	$ 18.8	$ 16.9	$ 16.5	$ 19.1	$ 16.9