Consolidated Statement of Changes in Equity - USD ($) $ in Millions		Total	Common Stock	Common Stock Class A Common Stock	Common Stock Class B Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Total Hubbell Shareholders' Equity	Non- controlling interest
Beginning of period at Dec. 31, 2014				$ 0.1	$ 0.5	$ 146.7	$ 1,944.1	$ (164.3)	$ 1,927.1	$ 8.6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		$ 282.1					277.3		277.3	4.8
Other comprehensive (loss) income		(59.9)						(59.9)	(59.9)
Stock-based compensation						16.3			16.3
Income tax windfall from stock-based awards, net						0.9			0.9
Acquisition/surrender of common shares						92.6			92.6
Cash dividends declared							(133.8)		(133.8)
Dividends to noncontrolling interest										(5.0)
Director's deferred compensation						6.8			6.8
Share reclassification			$ 0.6	(0.1)	(0.5)		(201.5)		(201.5)
End of period at Dec. 31, 2015			0.6	0.0	0.0	78.1	1,886.1	(224.2)	1,740.6	8.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		297.8					293.0		293.0	4.8
Other comprehensive (loss) income		(78.3)						(78.3)	(78.3)
Stock-based compensation						22.5			22.5
Income tax windfall from stock-based awards, net						4.8			4.8
Acquisition/surrender of common shares	[1]					90.4	155.5		245.9
Cash dividends declared							(144.3)		(144.3)
Dividends to noncontrolling interest										(2.8)
Director's deferred compensation						0.4			0.4
End of period at Dec. 31, 2016		1,603.2	0.6	0.0	0.0	15.4	1,879.3	(302.5)	1,592.8	10.4
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		249.9					243.1		243.1	6.8
Other comprehensive (loss) income		32.7						32.7	32.7
Stock-based compensation						22.3			22.3
Acquisition/surrender of common shares	[1]					27.2	72.1		99.3
Cash dividends declared							(157.9)		(157.9)
Dividends to noncontrolling interest										3.5
Director's deferred compensation						0.5			0.5
End of period at Dec. 31, 2017		$ 1,647.9	$ 0.6	$ 0.0	$ 0.0	$ 11.0	$ 1,892.4	$ (269.8)	$ 1,634.2	$ 13.7

[1] For accounting purposes, the Company treats repurchased shares as constructively retired when acquired and accordingly charges the purchase price against Common Stock par value, Additional paid-in capital, to the extent available, and Retained earnings. The change in Retained earnings of $72.1 million and $155.5 million in 2017 and 2016, respectively, reflects this accounting treatment.