Supplementary Financial Statement Information Supplementary Financial Statement Information (Interest Income and Interest Expense (Footnotes) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014
Variable Interest Entity, Not Primary Beneficiary [Member]
Interest Income and Interest Expense [Line Items]
Interest expense and interest income excluded, amount	$ 25	$ 38

The amount of income (loss) from operations derived by the reporting entity during the period from the Variable Interest Entity (VIE).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph d
-URI http://asc.fasb.org/extlink&oid=64801991&loc=d3e5747-111685

Name:	us-gaap_VariableInterestEntityActivityBetweenVIEAndEntityOperatingIncomeOrLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration