Reclassifications from Accumulated Other Comprehensive (Loss) Income - Schedule of changes in AOCI by component, net of tax (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Changes in the balance of Accumulated Other Comprehensive Income
Balances, period start			$ 1,104.9	$ 1,325.9
Balances, period end	$ 1,161.6	$ 1,187.0	1,161.6	1,187.0
Cash flow hedging items
Changes in the balance of Accumulated Other Comprehensive Income
Balances, period start	(7.2)	(39.7)	(21.8)	(28.5)
Other comprehensive income (loss) before reclassifications	5.5	(1.7)	9.4	(25.5)
Amounts reclassified from AOCI	1.7	7.4	12.4	20.0
Net other comprehensive income	7.2	5.7	21.8	(5.5)
Balances, period end	0.0	(34.0)	0.0	(34.0)
Pension and other postretirement benefit plan items
Changes in the balance of Accumulated Other Comprehensive Income
Balances, period start	(321.2)	(249.4)	(344.3)	(256.8)
Other comprehensive income (loss) before reclassifications	0.0	0.0	11.7	0.0
Amounts reclassified from AOCI	5.7	3.8	17.1	11.2
Net other comprehensive income	5.7	3.8	28.8	11.2
Balances, period end	(315.5)	(245.6)	(315.5)	(245.6)
Unrealized losses on available-for- sale securities
Changes in the balance of Accumulated Other Comprehensive Income
Balances, period start	(0.3)	(0.3)	(0.3)	(0.3)
Other comprehensive income (loss) before reclassifications	0.0	0.0	0.0	0.0
Amounts reclassified from AOCI	0.0	0.0	0.0	0.0
Net other comprehensive income	0.0	0.0	0.0	0.0
Balances, period end	(0.3)	(0.3)	(0.3)	(0.3)
Foreign currency items
Changes in the balance of Accumulated Other Comprehensive Income
Balances, period start	(48.2)	(48.2)	(43.5)	(42.6)
Other comprehensive income (loss) before reclassifications	2.6	7.7	(2.1)	2.1
Amounts reclassified from AOCI	0.0	0.0	0.0	0.0
Net other comprehensive income	2.6	7.7	(2.1)	2.1
Balances, period end	(45.6)	(40.5)	(45.6)	(40.5)
Accumulated Other Comprehensive (Loss) Income
Changes in the balance of Accumulated Other Comprehensive Income
Balances, period start	(376.9)	(337.6)	(409.9)	(328.2)
Other comprehensive income (loss) before reclassifications	8.1	6.0	19.0	(23.4)
Amounts reclassified from AOCI	7.4	11.2	29.5	31.2
Net other comprehensive income	15.5	17.2	48.5	7.8
Balances, period end	$ (361.4)	$ (320.4)	$ (361.4)	$ (320.4)