Total Equity - Composition of Equity (Details) - USD ($) $ / shares in Units, $ in Millions	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Dec. 31, 2016
Stockholders' Equity Note [Abstract]
Common Stock – authorized 200.0 shares; issued and outstanding 54.8 and 54.9 shares	$ 0.5	$ 0.6
Additional paid-in capital	2.9	11.0
Retained earnings	1,967.0	1,892.4
Accumulated other comprehensive loss:
Pension and post retirement benefit plan adjustment, net of tax	(172.6)	(176.5)
Cumulative translation adjustment	(112.7)	(91.9)
Unrealized gain (loss) on investment, net of tax	(1.0)	(0.6)
Cash flow hedge gain (loss), net of tax	0.8	(0.8)
Total Accumulated other comprehensive loss	(285.5)	(269.8)
Hubbell shareholders’ equity	1,684.9	1,634.2
Noncontrolling interest	16.9	13.7
Total Equity	$ 1,701.8	$ 1,647.9	$ 1,603.2	$ 1,603.2
Common stock par value per share (USD per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	200,000,000.0	200,000,000.0
Common stock, shares, issued (in shares)	54,800,000	54,900,000
Common stock, shares, outstanding (in shares)	54,800,000	54,900,000