Reclassifications from Accumulated Other Comprehensive (Loss) Income (AOCI) - Schedule of changes in AOCI by component, net of tax (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Changes in the balance of Accumulated Other Comprehensive Income
Balances, period start			$ 1,485.9	$ 1,198.6
Cumulative adjustment upon adoption of ASU 2017-12 reclassified to reinvested earnings	$ 0.0	$ 0.0	(1.0)	0.0
Balances, period end	1,505.5	1,336.8	1,505.5	1,336.8
Cash flow hedging items
Changes in the balance of Accumulated Other Comprehensive Income
Balances, period start	(0.2)	5.8	23.8	(2.3)
Cumulative adjustment upon adoption of ASU 2017-12 reclassified to reinvested earnings			(1.0)
Other comprehensive income (loss) before reclassifications	(14.9)	14.9	(39.1)	21.0
Amounts reclassified from AOCI	(0.5)	0.1	0.7	2.1
Net other comprehensive (loss) income	(15.4)	15.0	(39.4)	23.1
Balances, period end	(15.6)	20.8	(15.6)	20.8
Pension and other postretirement benefit plan items
Changes in the balance of Accumulated Other Comprehensive Income
Balances, period start	(218.7)	(296.9)	(220.4)	(299.0)
Cumulative adjustment upon adoption of ASU 2017-12 reclassified to reinvested earnings			0.0
Other comprehensive income (loss) before reclassifications	0.0	0.0	0.0	0.0
Amounts reclassified from AOCI	1.7	2.5	3.4	4.6
Net other comprehensive (loss) income	1.7	2.5	3.4	4.6
Balances, period end	(217.0)	(294.4)	(217.0)	(294.4)
Unrealized (losses) gains on available-for-sale securities
Changes in the balance of Accumulated Other Comprehensive Income
Balances, period start	0.0	(0.3)	(0.3)	(0.3)
Cumulative adjustment upon adoption of ASU 2017-12 reclassified to reinvested earnings			0.0
Other comprehensive income (loss) before reclassifications	0.0	0.0	0.3	0.0
Amounts reclassified from AOCI	0.0	0.0	0.0	0.0
Net other comprehensive (loss) income	0.0	0.0	0.3	0.0
Balances, period end	0.0	(0.3)	0.0	(0.3)
Foreign currency items
Changes in the balance of Accumulated Other Comprehensive Income
Balances, period start	(42.2)	(39.7)	(42.9)	(41.5)
Cumulative adjustment upon adoption of ASU 2017-12 reclassified to reinvested earnings			0.0
Other comprehensive income (loss) before reclassifications	(2.7)	(1.5)	(2.0)	0.3
Amounts reclassified from AOCI	0.0	0.0	0.0	0.0
Net other comprehensive (loss) income	(2.7)	(1.5)	(2.0)	0.3
Balances, period end	(44.9)	(41.2)	(44.9)	(41.2)
Accumulated Other Comprehensive (Loss) Income
Changes in the balance of Accumulated Other Comprehensive Income
Balances, period start	(261.1)	(331.1)	(239.8)	(343.1)
Cumulative adjustment upon adoption of ASU 2017-12 reclassified to reinvested earnings			(1.0)
Other comprehensive income (loss) before reclassifications	(17.6)	13.4	(40.8)	21.3
Amounts reclassified from AOCI	1.2	2.6	4.1	6.7
Net other comprehensive (loss) income	(16.4)	16.0	(37.7)	28.0
Balances, period end	$ (277.5)	$ (315.1)	$ (277.5)	$ (315.1)

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Represents the quantification of the effect of adopting the new accounting standard or change in accounting principle expected by the entity to have a significant effect on the entity's financial statements.

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Amount after tax, before reclassification adjustments of other comprehensive income (loss).

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Amount after tax and reclassification adjustments of other comprehensive income (loss).

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Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity.

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