New Accounting Guidance - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Effective income tax rate reconciliation, share-based compensation, excess tax benefit, amount	$ 44	$ 18

Effective Income Tax Rate Reconciliation, Share-based Compensation, Excess Tax Benefit, Amount

No definition available.

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