Regulatory Assets and Liabilities (Narrative) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011
Regulatory assets represented past expenditures not earning return	$ 198

Regulatory Assets Past Expenditures Not Earning Return

No definition available.

Name:	d_RegulatoryAssetsPastExpendituresNotEarningReturn
Namespace Prefix:	d_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant