Income Taxes (Deferred Income Taxes Narrative) (Details) $ in Millions	12 Months Ended
Dec. 31, 2016 USD ($)
Income Tax Disclosure [Abstract]
Valuation allowance change	$ 62

Amount of increase (decrease) in the valuation allowance for a specified deferred tax asset.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 45
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=75116654&loc=d3e32123-109318

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration