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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Summary of Significant Accounting Policies (details) - Acquisition (USD $)	0 Months Ended
	Nov. 01, 2013	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition
Goodwill acquired		$ 3,611,000,000us-gaap_Goodwill	$ 3,634,000,000us-gaap_Goodwill
Dominion [Member]
Business Acquisition
Purchase price	1,035,000,000
Assets acquired	3,910,000,000
Liabilities assumed	2,880,000,000
Intangible assets acquired	16,000,000
Goodwill acquired	273,000,000
Value of business acquired (VOBA)	$ 76,000,000