Rosetta Merger - Pro Forma Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Business Combinations [Abstract]
Revenues	$ 828	$ 1,557	$ 2,582	$ 4,828
Net income	$ (202)	$ 542	$ (338)	$ 1,039
Earnings per share:
Basic (in dollars per share)	$ (0.44)	$ 1.37	$ (0.79)	$ 2.63
Diluted (in dollars per share)	$ (0.44)	$ 1.35	$ (0.79)	$ 2.59

The pro forma basic net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (h)(2)-(3)

-URI http://asc.fasb.org/extlink&oid=25497992&loc=d3e1392-128463

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The pro forma diluted net income per share for a period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma net Income or Loss for the period as if the business combination or combinations had been completed at the beginning of a period.

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The pro forma revenue for a period as if the business combination or combinations had been completed at the beginning of the period.

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