Financial Instruments and Guarantees with Off-Balance-Sheet Risk (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011	Dec. 31, 2011
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	$ 2,204.1
Financial Instruments and Guarantees with Off-Balance-Sheet Risk (Textuals) [Abstract]
Amount in letters of credit and surety bonds related to collateral for surety companies, road maintenance, performance guarantees and other operations	213.1
Time Period Of Lease That Permits The Partnership To Purchase The Terminal	30 years
Maximum capacity of the securitization program	275.0
Amount available under the securitization program	53.1
Total consideration received by Company related to accounts receivable sold under securitization program	1,094.5
Cash up front from sale of receivables	618.1
Additional cash upon collection of underlying receivables	145.4
Non collected receivables	331.0
Reduction in accounts receivable as a result of securitization	75.0			150.0
Expense associated with securitization transactions	0.5		0.6
Dominion Terminal Associates Partnership [Member]
Financial Instruments and Guarantees with Off-Balance-Sheet Risk (Textuals) [Abstract]
Equity Method Investment, Ownership Percentage	37.50%
Number of Letters of Credit Supporting Reimbursement Obligation	4
Maximum reimbursement obligation to commercial bank related to Dominion Terminals	42.7
Pension Plans Agreement With PBG and TXU Europe [Member]
Financial Instruments and Guarantees with Off-Balance-Sheet Risk (Textuals) [Abstract]
Letter of credit maintained by the Company in favor of the PBGC	37.0
Number of benefit pension plans	2
Guarantee in place from TXU Europe Limited	110.0
Reclamation Obligations [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	1,728.8
Property Lease Guarantee [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	106.4
Workers' Compensation Obligations [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	76.1
Guarantee Type, Other [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	292.8	[1]
Self bonding [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	931.5
Self bonding [Member] | Reclamation Obligations [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	931.5
Self bonding [Member] | Property Lease Guarantee [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	0
Self bonding [Member] | Workers' Compensation Obligations [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	0
Self bonding [Member] | Guarantee Type, Other [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	0	[1]
Surety bonds [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	816.9
Surety bonds [Member] | Reclamation Obligations [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	609.7
Surety bonds [Member] | Property Lease Guarantee [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	106.4
Surety bonds [Member] | Workers' Compensation Obligations [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	13.5
Surety bonds [Member] | Guarantee Type, Other [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	87.3	[1]
Bank guarantees [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	291.9
Bank guarantees [Member] | Reclamation Obligations [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	187.6
Bank guarantees [Member] | Property Lease Guarantee [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	0
Bank guarantees [Member] | Workers' Compensation Obligations [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	0
Bank guarantees [Member] | Guarantee Type, Other [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	104.3	[1]
Letters of credit [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	84.1
Letters of credit [Member] | Reclamation Obligations [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	0
Letters of credit [Member] | Property Lease Guarantee [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	0
Letters of credit [Member] | Workers' Compensation Obligations [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	62.6
Letters of credit [Member] | Guarantee Type, Other [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	21.5	[1]
Bilateral cash collateralization agreements [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	79.7
Bilateral cash collateralization agreements [Member] | Reclamation Obligations [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	0
Bilateral cash collateralization agreements [Member] | Property Lease Guarantee [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	0
Bilateral cash collateralization agreements [Member] | Workers' Compensation Obligations [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	0
Bilateral cash collateralization agreements [Member] | Guarantee Type, Other [Member]
Guarantee Obligations [Line Items]
Guarantor Obligations, Current Carrying Value	$ 79.7	[1]

[1] Other includes bilateral cash collateralization agreements described below and an additional $213.1 million in bank guarantees, surety bonds and letters of credit related to collateral for surety companies, road maintenance, performance guarantees and other operations.