Retirement Benefits - Obligations and Funded Status (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Changes in the benefit obligation [Roll Forward]
Net experience gains (losses) arising during the year	$ 6.0	$ 0
Reclassification adjustment for amortization of prior net experience loss included in net income	21.5	11.6
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Prior Service Cost (Credit) Arising During Period, before Tax	0	0
Reclassification adjustment for amortization of prior service cost (credit) included in net income	0.9	0.9
US Plans [Member]
Changes in the benefit obligation [Roll Forward]
Service cost	0	0
Interest cost	11.0	11.5
Non-US Plans [Member]
Changes in the benefit obligation [Roll Forward]
Service cost	2.6	2.8
Interest cost	4.1	4.3
UMWA plans [Member]
Changes in the benefit obligation [Roll Forward]
Interest cost	5.6	6.1
Pension plan [Member]
Changes in the benefit obligation [Roll Forward]
Service cost	2.6	2.8
Interest cost	15.1	15.8
Retirement benefits other than pension [Member]
Changes in the benefit obligation [Roll Forward]
Interest cost	$ 6.4	$ 6.8