Debt (Details) - USD ($) $ in Millions	9 Months Ended
	Mar. 31, 2016	Jul. 15, 2015
Debt
Outstanding balance	$ 2,800.0
2017 Senior Notes
Debt
Unsecured notes outstanding	$ 350.0
Interest rate (as a percent)	9.75%
Interest expense	$ 0.0
2017 Senior Notes | Liabilities Subject to Compromise
Debt
Accrued interest		$ 14.1
2019 Senior Notes
Debt
Interest rate (as a percent)	7.25%
Interest expense	$ 0.0
Outstanding balance	$ 577.9
2019 Senior Notes | Liabilities Subject to Compromise
Debt
Accrued interest		24.3
2020 Senior Notes
Debt
Interest rate (as a percent)	7.50%
Interest expense	$ 0.0
Outstanding balance	$ 222.1
2020 Senior Notes | Liabilities Subject to Compromise
Debt
Accrued interest		$ 5.5