Retirement Benefit Plans - Change in Plan Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Change in plan assets:
Return on plan assets	$ 10.8	$ 21.1
Pension Plan, Defined Benefit [Member]
Change in plan assets:
Fair value of plan assets at beginning of year	1,772.4	2,870.0
Actual return on plan assets	23.0	250.5
Employee contributions	0.0	0.0
Return on plan assets	4.4	4.5
International plan exchange rate change	0.0	0.0
Defined Benefit Plan, Business Combinations and Acquisitions, Plan Assets	17.6	0.0
Defined Benefit Plan, Settlements, Plan Assets	(1,162.8)	0.0
Benefits paid	(100.9)	(234.6)
Spinoff of Steel Change in Plan Assets	0.0	(1,118.0)
Fair value of plan assets at end of year	553.7	1,772.4
Funded status at end of year	(36.2)	68.5
International Plans [Member]
Change in plan assets:
Fair value of plan assets at beginning of year	349.4	420.6
Actual return on plan assets	4.5	42.2
Employee contributions	0.0	0.3
Return on plan assets	6.4	16.6
International plan exchange rate change	(23.6)	(21.2)
Defined Benefit Plan, Business Combinations and Acquisitions, Plan Assets	0.0	0.0
Defined Benefit Plan, Settlements, Plan Assets	(14.5)	0.0
Benefits paid	(17.6)	(23.5)
Spinoff of Steel Change in Plan Assets	0.0	(85.6)
Fair value of plan assets at end of year	304.6	349.4
Funded status at end of year	$ (33.5)	$ (66.3)