Retirement Benefits - Obligations and Funded Status (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Defined Benefit Plan Change In Net Actuarial Gains And Losses In Other Comprehensive Income [Roll Forward]
Net experience gains (losses) arising during the year	$ (3.8)	$ (1.0)	$ (11.1)	$ (4.7)
Reclassification adjustment for amortization of prior net experience loss included in net income	18.6	12.1	56.6	36.3
Defined Benefit Plan Change In Net Prior Service Cost Credit In Other Comprehensive Income [Roll Forward]
Prior service cost (credit) from plan amendment during the year	(0.2)	0	12.0	0
Reclassification adjustment for amortization of prior service cost (credit) included in net income	(1.1)	(0.9)	(2.9)	(2.7)
US Plans [Member]
Changes in the benefit obligation [Roll Forward]
Service cost	0	0	0	0
Interest cost	11.0	11.6	33.0	34.7
Non-US Plans [Member]
Changes in the benefit obligation [Roll Forward]
Service cost	2.8	2.5	8.2	7.8
Interest cost	5.0	4.3	13.9	12.9
Umwa Plans Postretirement Medical [Member]
Changes in the benefit obligation [Roll Forward]
Service cost	0	0	0	0
Interest cost	5.6	5.9	16.8	17.9
Pension plan [Member]
Changes in the benefit obligation [Roll Forward]
Service cost	2.8	2.5	8.2	7.8
Interest cost	16.0	15.9	46.9	47.6
Retirement benefits other than pension [Member]
Changes in the benefit obligation [Roll Forward]
Service cost	0.2	0	0.3	0
Interest cost	$ 6.3	$ 6.6	$ 19.0	$ 20.0