Investments (Fair Value of our Marketable Debt Securities by Contractual Maturity) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Due in one year or less	$ 128
Due after one year through five years	357
Due after five years through ten years	362
Due after ten years	391
Total	1,238
Virginia Electric and Power Company
Schedule of Available-for-sale Securities [Line Items]
Due in one year or less	31
Due after one year through five years	163
Due after five years through ten years	196
Due after ten years	176
Total	$ 566