Income Taxes - Schedule of Reconciliation of the Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Unrecognized Tax Benefits
Balance at beginning of period	$ 249	$ 236	$ 279
Increases for tax positions of prior years	2	25	3
Decreases for tax positions of prior years	(1)	(4)	(29)
Increases for tax positions related to the current period	0	1	1
Decreases for cash settlements with taxing authorities	(1)	(3)	(13)
Decreases due to the lapse of the applicable statute of limitations	(9)	(6)	(5)
Balance at end of period	$ 240	$ 249	$ 236