Employee Benefit Plans (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Summary of net periodic pension cost
Service cost	$ 0.5	$ 0.4	$ 0.9	$ 0.8
Interest cost	0.6	0.7	1.3	1.3
Expected return on plan assets	(0.7)	(0.7)	(1.3)	(1.4)
Amortization of acturial loss	0.3		0.5
Net periodic benefit cost	$ 0.7	$ 0.4	$ 1.4	$ 0.7