Retirement Benefit Plans - Change in Benefit Obligation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Change in benefit obligation:
Benefit obligation at beginning of year	$ 110.0
Defined Benefit Plan, Settlements, Benefit Obligation	(1,100.0)	$ (110.0)
Benefit obligation at end of year		110.0
Pension Plan, Defined Benefit [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	1,703.9	2,642.4
Service cost	15.4	21.5	$ 35.7
Interest cost	45.6	98.3	116.2
Amendments	0.0	0.0
Actuarial losses (gains)	68.8	239.6
Employee contributions	0.0	0.0
Defined Benefit Plan, Foreign Currency Exchange Rate Gain (Loss)	0.0	0.0
Defined Benefit Plan, Curtailments	0.0	0.0
Benefits paid	(100.9)	(234.6)
Defined Benefit Plan, Special Termination Benefits	0.0	0.0	0.0
Defined Benefit Plan, Settlements, Benefit Obligation	(1,162.8)	0.0
Defined Benefit Plan, Business Combinations and Acquisitions, Benefit Obligation	19.9	0.0
Spinoff of Steel Change in Benefit Obligation	0.0	(1,063.3)
Benefit obligation at end of year	589.9	1,703.9	2,642.4
International Plans [Member]
Change in benefit obligation:
Benefit obligation at beginning of year	415.7	491.1
Service cost	2.2	2.4	2.8
Interest cost	12.3	17.7	18.5
Amendments	0.0	0.3
Actuarial losses (gains)	(31.6)	38.7
Employee contributions	0.0	0.3
Defined Benefit Plan, Foreign Currency Exchange Rate Gain (Loss)	(29.5)	(29.5)
Defined Benefit Plan, Curtailments	0.5	0.0
Benefits paid	(17.6)	(23.5)
Defined Benefit Plan, Special Termination Benefits	0.6	0.0	0.0
Defined Benefit Plan, Settlements, Benefit Obligation	(14.5)	0.0
Defined Benefit Plan, Business Combinations and Acquisitions, Benefit Obligation	0.0	0.0
Spinoff of Steel Change in Benefit Obligation	0.0	(81.8)
Benefit obligation at end of year	$ 338.1	$ 415.7	$ 491.1