Pension and Other Postretirement Benefits (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended	9 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2015	Mar. 31, 2014
Pension Plans
Pension and Other Postretirement Benefit Disclosures
Service cost	$ 8.0	$ 8.0		$ 24.0	$ 24.2
Interest cost	13.5	14.3		40.5	43.0
Expected return on plan assets	(17.2)	(15.7)		(51.6)	(47.1)
Amortization of net loss	4.2	5.5		12.6	16.3
Amortization of prior service cost	0.1	0.1		0.3	0.4
Net periodic benefit costs	8.6	12.2		25.8	36.8
Capitalized periodic benefit costs			2.2		2.2
Contributions				5.5	4.6
Defined benefit pension plan, expected contributions during the remainder of fiscal year 2015				1.7
Other Postretirement Plans
Pension and Other Postretirement Benefit Disclosures
Service cost	1.1	1.0		3.3	3.0
Interest cost	3.0	3.1		9.0	9.3
Expected return on plan assets	(1.7)	(1.6)		(5.0)	(4.8)
Amortization of net loss	0.5	0.3		1.5	0.9
Amortization of prior service cost	0	0		0	0
Net periodic benefit costs	$ 2.9	$ 2.8		$ 8.8	$ 8.4