Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Supplemental Cash Flow Elements [Abstract]
Cash paid for income taxes, net of refunds	$ 20	$ 34	$ 138
Cash paid for interest	$ 193	$ 201	$ 19