Financial Instruments (Details) $ in Thousands		12 Months Ended
		Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Sep. 24, 2013 USD ($)
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk		$ 2,476,500
Financial Instruments and Guarantees with Off-Balance-Sheet Risk (Textuals) [Abstract]
Letters of credit outstanding					$ 94,700
Amount in bank guarantees, letters of credit and surety bonds related to road maintenance, performance guarantees and other operations		188,200
Amount in letters of credit issued as collateral to support surety bonds		75,900
Maximum capacity of the securitization program		275,000
Amount available under the securitization program		0
Total consideration received by Company related to accounts receivable sold under securitization program		3,703,200
Cash up front from sale of receivables		2,595,100
Additional cash upon collection of underlying receivables		1,096,400
Non collected receivables		11,700
Reduction in accounts receivable as a result of securitization activity		168,500	$ 30,000
Expense associated with securitization transactions		1,800	1,500	$ 1,500
DTA and PBGC [Member]
Financial Instruments and Guarantees with Off-Balance-Sheet Risk (Textuals) [Abstract]
Letters of credit outstanding		$ 79,700
Dominion Terminal Associates Partnership [Member]
Financial Instruments and Guarantees with Off-Balance-Sheet Risk (Textuals) [Abstract]
Ownership percentage of equity method investment		37.50%
DTA Lease Term		30
Number of letters of credit supporting reimbursement obligation		4
Maximum reimbursement obligation to commercial bank		$ 42,700
Pension Plans Agreement With PBG and TXU Europe [Member]
Financial Instruments and Guarantees with Off-Balance-Sheet Risk (Textuals) [Abstract]
Defined benefit pension plans requiring special contributions		2
Letter of credit maintained by the Company in favor of the PBGC		$ 37,000
Guarantee in place from TXU Europe Limited		110,000
Reclamation Obligations [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk		2,023,100
Coal Lease Obligations [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk		110,500
Workers' Compensation Obligations [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk		75,000
Other [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk	[1]	267,900
Financial Standby Letter of Credit [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk		429,200
Self bonding [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk		1,430,800
Self bonding [Member] | Reclamation Obligations [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk		1,430,800
Self bonding [Member] | Coal Lease Obligations [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk		0
Self bonding [Member] | Workers' Compensation Obligations [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk		0
Self bonding [Member] | Other [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk	[1]	0
Self bonding [Member] | Financial Standby Letter of Credit [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk		0
Surety Bond [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk		437,700
Surety Bond [Member] | Reclamation Obligations [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk		293,200
Surety Bond [Member] | Coal Lease Obligations [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk		110,500
Surety Bond [Member] | Workers' Compensation Obligations [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk		19,100
Surety Bond [Member] | Other [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk	[1]	14,900
Surety Bond [Member] | Financial Standby Letter of Credit [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk	[2]	75,600
Bank Guarantees [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk		401,700
Bank Guarantees [Member] | Reclamation Obligations [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk		299,100
Bank Guarantees [Member] | Coal Lease Obligations [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk		0
Bank Guarantees [Member] | Workers' Compensation Obligations [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk		0
Bank Guarantees [Member] | Other [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk	[1]	102,600
Bank Guarantees [Member] | Financial Standby Letter of Credit [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk		353,600
Letters of credit [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk		206,300
Letters of credit [Member] | Reclamation Obligations [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk		0
Letters of credit [Member] | Coal Lease Obligations [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk		0
Letters of credit [Member] | Workers' Compensation Obligations [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk		55,900
Letters of credit [Member] | Other [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk	[1]	150,400
Letters of credit [Member] | Financial Standby Letter of Credit [Member]
Guarantee Obligations [Line Items]
Financial instruments with off balance sheet risk		0
Performance Guarantee [Member]
Financial Instruments and Guarantees with Off-Balance-Sheet Risk (Textuals) [Abstract]
Liability for reclamation and bonding guarantee		$ 38,400	$ 44,700

[1] Other includes the $79.7 million in letters of credit related to Dominion Terminal Associates and the PBGC, as described below, and an additional $188.2 million in bank guarantees, letters of credit and surety bonds related to road maintenance, performance guarantees and other operations.

[2] A total of $75.9 million of letters of credit issued as collateral to support surety bonds related to Patriot have been excluded from above as they no longer represent off-balance sheet obligations as discussed in Note 25. "Matters Related to the Bankruptcy of Patriot Coal Corporation".