Income Taxes Income Taxes (Deferred Tax Liability) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014
Deferred income tax assets:
Inventory	$ 0.2
Accrued expenses	0.6
Asset retirement obligations	2.2
Net operating loss carryforward-non current	42.7
Total deferred tax assets	45.7
Deferred income tax liabilities:
Property, plant, equipment, and intangibles assets-long term	522.9
Other assets	8.1
Total deferred tax liabilities	531.0
Net deferred tax liability	$ 485.3