Variable Interest Entities - Summary of Assets and Liabilities Related to Consolidated Variable Interest Entities (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Variable interest entities [Member]
Variable Interest Entity [Line Items]
Consolidated Assets	$ 305	$ 320
Consolidated Liabilities	160	160
Other assets [Member] \| Limited partnership investments [Member]
Variable Interest Entity [Line Items]
Consolidated Assets	305	320
Long-term debt [Member] \| Limited partnership investments [Member]
Variable Interest Entity [Line Items]
Consolidated Liabilities	92	92
Interest, taxes and other liabilities [Member] \| Limited partnership investments [Member]
Variable Interest Entity [Line Items]
Consolidated Liabilities	$ 68	$ 68

The carrying amount of the consolidated Variable Interest Entity's assets included in the reporting entity's statement of financial position.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (bb)
-URI http://asc.fasb.org/extlink&oid=64801991&loc=d3e5710-111685

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- Definition

The carrying amount of the consolidated Variable Interest Entity's liabilities included in the reporting entity's statement of financial position.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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