Income Taxes (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2016	Jun. 30, 2016
Income Taxes [Abstract]
Increase in valuation allowance	$ 216	$ 647
Projected cumulative loss period evaluated for objective negative evidence		3 years

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

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