Liabilities Subject to Compromise (Details) - USD ($)		Sep. 30, 2016	Dec. 31, 2015
Schedule of liabilities subject to compromise [Line Items]
Liabilities subject to compromise		$ 8,331,600,000	$ 0
Long-term Debt [Member]
Schedule of liabilities subject to compromise [Line Items]
Liabilities subject to compromise	[1]	7,920,400,000
Interest Payable [Member]
Schedule of liabilities subject to compromise [Line Items]
Liabilities subject to compromise		172,600,000
Accounts Payable [Member]
Schedule of liabilities subject to compromise [Line Items]
Liabilities subject to compromise		77,300,000
Environmental liabilities
Schedule of liabilities subject to compromise [Line Items]
Liabilities subject to compromise		62,900,000
Other Pension Plan, Postretirement or Supplemental Plans [Member]
Schedule of liabilities subject to compromise [Line Items]
Liabilities subject to compromise	[2]	34,000,000
UMWA Plan liability
Schedule of liabilities subject to compromise [Line Items]
Liabilities subject to compromise	[3]	25,000,000
Property Taxes [Member]
Schedule of liabilities subject to compromise [Line Items]
Liabilities subject to compromise		7,100,000
Accrued Liabilities [Member]
Schedule of liabilities subject to compromise [Line Items]
Liabilities subject to compromise		32,300,000
Debt [Member] | Long-term Debt [Member]
Schedule of liabilities subject to compromise [Line Items]
Liabilities subject to compromise	[1]	7,601,600,000
Hedge terminations [Member] | Long-term Debt [Member]
Schedule of liabilities subject to compromise [Line Items]
Liabilities subject to compromise	[1]	257,300,000
Liabilities secured by prepetition letters of credit [Member] | Long-term Debt [Member]
Schedule of liabilities subject to compromise [Line Items]
Liabilities subject to compromise	[1]	$ 61,500,000

[1] Includes $7,601.6 million of debt, $257.3 million of derivative contract terminations, and $61.5 million of liabilities secured by prepetition letters of credit.

[2] Includes liabilities for unfunded non-qualified pension plans, all the participants of which are former employees.

[3] Refer to Note 20. "Matters Related to the Bankruptcy of Patriot Coal Corporation" for additional information.