Retirement Benefits - Obligations and Funded Status (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Changes in plan assets [Roll Forward]
Employer contributions			$ 26.2
US Plans [Member]
Changes in the benefit obligation [Roll Forward]
Service cost	0	0	0	0
Interest cost	11.3	10.5	22.7	21.1
Non-US Plans [Member]
Changes in the benefit obligation [Roll Forward]
Service cost	3.2	3.8	6.7	7.4
Interest cost	4.6	4.8	10.4	9.6
UMWA Plans Postretirement Medical [Member]
Changes in the benefit obligation [Roll Forward]
Service cost	0	0	0	0
Interest cost	4.4	4.9	9.2	9.9
Pension plan [Member]
Changes in the benefit obligation [Roll Forward]
Service cost	3.2	3.8	6.7	7.4
Interest cost	15.9	15.3	33.1	30.7
Retirement benefits other than pension [Member]
Changes in the benefit obligation [Roll Forward]
Service cost	0.1	0.1	0.1	0.2
Interest cost	$ 4.8	$ 5.4	$ 10.2	$ 10.9