Employee Benefit Plans (Details) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Employee Benefit Plans
Service cost	$ 1.6	$ 1.3	$ 3.9	$ 3.3
Interest cost	1.8	1.5	4.6	4.0
Expected return on plan assets	(1.1)	(0.9)	(2.9)	(2.7)
Amortization of prior service costs	0.2		0.2	0.5
Net periodic benefit costs	2.5	1.9	5.8	5.1
Contribution to defined benefit plans			2.6
Estimated contribution to defined benefit plans during the remainder of the fiscal year	$ 0.8		$ 0.8