Foreign Operations (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Foreign operations data
Revenues	$ 356.7	$ 360.7	$ 359.4	$ 317.0	$ 356.4	$ 349.7	$ 349.5	$ 305.3	$ 1,393.8	$ 1,360.9	$ 1,376.9
Identifiable assets	$ 8,285.1				7,616.7				$ 8,285.1	7,616.7	7,422.4
Foreign Operations (Textual) [Abstract]
Maximum percentage of consolidated revenues derive from any individual foreign country									10.00%
Percentage of company's identifiable assets	10.00%								10.00%
Foreign [Member]
Foreign operations data
Revenues									$ 331.1	333.5	324.0
Identifiable assets	$ 2,624.5				2,470.9				2,624.5	2,470.9	2,407.2
United States [Member]
Foreign operations data
Revenues									1,062.7	1,027.4	1,052.9
Identifiable assets	$ 5,660.6				$ 5,145.8				$ 5,660.6	$ 5,145.8	$ 5,015.2