Total Equity Total Equity - Changes in Equity (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	$ 1,798.9
Net income	73.8	$ 59.8
Other comprehensive (loss) income	$ 8.3
Cash dividends per common share (USD per share)	$ 0.84	$ 0.77
Ending equity	$ 1,826.9
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	1.3	11.0
Stock-based compensation	4.1	5.1
Acquisition/surrender of common shares	(5.3)	(6.1)
Director's deferred compensation	0.1	0.1
Ending equity	0.2	10.1
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	2,064.4	1,892.4
Net income	72.3	58.3
Reclassification of stranded tax effects	30.0	0.6
Acquisition/surrender of common shares	(6.3)	0.0
Cash dividends declared	(45.7)	(42.3)
Ending equity	2,114.7	1,909.0
Accumulated Other Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	(285.7)	(269.8)
Other comprehensive (loss) income	8.3	12.1
Reclassification of stranded tax effects	(30.0)
Ending equity	(307.4)	(257.7)
Total Hubbell Shareholders' Equity
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	1,780.6	1,634.2
Net income	72.3	58.3
Other comprehensive (loss) income	8.3	12.1
Stock-based compensation	4.1	5.1
Reclassification of stranded tax effects		0.6
Acquisition/surrender of common shares	(11.6)	(6.1)
Cash dividends declared	(45.7)	(42.3)
Director's deferred compensation	0.1	0.1
Ending equity	1,808.1	1,662.0
Non- controlling interest
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning equity	18.3	13.7
Net income	1.5	1.5
Dividends to noncontrolling interest	(1.0)	(1.1)
Aclara noncontrolling interest		2.4
Ending equity	$ 18.8	$ 16.5