Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Commitments and Contingencies Disclosure [Abstract]
Defined contribution plan, contributions	$ 22	$ 19	$ 17

Defined Contribution Plan and Deferred Profit Sharing Plan, Employer Contribution Amount

No definition available.

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