- Product Class Data (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net Sales:
Net sales	$ 917.7	$ 950.5	$ 948.3	$ 852.3	$ 854.2	$ 907.4	$ 908.8	$ 834.8	$ 3,668.8	$ 3,505.2	$ 3,390.4
Electrical Systems
Net Sales:
Net sales									1,597.1	1,514.4	1,476.7
Lighting
Net Sales:
Net sales									935.7	945.8	911.6
Power
Net Sales:
Net sales									$ 1,136.0	$ 1,045.0	$ 1,002.1