Income Taxes (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Income Tax Examination [Line Items]
Effective income tax rate	2.20%	11.90%
Increase (decrease) of income tax expense	$ (25.4)
Increase (decrease) in valuation allowance	(41.6)
Increase (decrease) in the effect of permanent differences	9.4
Filings in excess of amounts previously recorded	8.0
Investment tax credit	45.9
Unrecognized tax benefit	23.5
Net unrecognized tax benefit excluding deferred tax assets	150.9	$ 155.1
Possible decrease in tax expense in next 12 months	3.8
Taxes paid on cash distribution	15.9	$ 12.1
Domestic Tax Authority
Income Tax Examination [Line Items]
Operating loss carryforward	53.3
Foreign Tax Authority
Income Tax Examination [Line Items]
Operating loss carryforward	621.8
Non-capital loss carryforwards with no expiry date	$ 63.2