Accounts Payable and Accrued Expenses (Details) - USD ($) $ in Millions		Dec. 31, 2016	Dec. 31, 2015
Accounts payable and accrued expenses [Line Items]
Trade accounts payable		$ 288.6	$ 333.3
Commodity and foreign currency hedge contracts		0.0	231.7
Other accrued expenses		190.1	225.8
Accrued payroll and related benefits		201.2	191.9
Accrued royalties		119.6	135.9
Payable to voluntary employee beneficiary association for certain Patriot retirees	[1]	0.0	75.0
Accrued royalties		62.8	41.0
Accrued interest		1.2	68.8
Asset Retirement Obligations		41.0	25.5
Accrued environmental cleanup-related costs		0.0	23.9
Accounts Payable, Other		0.0	2.3
Workers' compensation obligations		7.8	8.6
Income taxes payable		6.2	6.8
Accrued health care insurance		16.0	15.8
Liabilities associated with discontinued operations		55.9	60.0
Total accounts payable and accrued expenses		$ 990.4	$ 1,446.3

[1] Refer to Note 27. "Matters Related to the Bankruptcy of Patriot Coal Corporation" herein for additional details related to this transaction.