Pension and Other Postretirement Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011
Pension and Other Postretirement Benefit Disclosures
Contributions			$ 57.9	$ 15.4
Pension Plans
Pension and Other Postretirement Benefit Disclosures
Service cost	8.0	5.5	16.1	11.1
Interest cost	13.3	12.3	26.5	24.6
Expected return on plan assets	(13.7)	(13.0)	(27.4)	(26.0)
Amortization of net loss	7.0	4.3	14.0	8.7
Amortization of prior service cost (benefit)	0.2	0.2	0.4	0.4
Net pension expense	14.8	9.3	29.6	18.8
Defined benefit pension plan, expected contributions	24.0		24.0
Other Postretirement Plans
Pension and Other Postretirement Benefit Disclosures
Service cost	1.1	0.7	2.2	1.4
Interest cost	3.0	2.7	6.1	5.4
Expected return on plan assets	(1.6)	(1.6)	(3.2)	(3.2)
Amortization of net loss	0.8	0.6	1.6	1.2
Amortization of prior service cost (benefit)	(1.0)	(1.9)	(2.0)	(3.9)
Net pension expense	$ 2.3	$ 0.5	$ 4.7	$ 0.9