Summary of Changes in Other Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]
Intangible assets, beginning balance	$ 493
Intangible assets, ending balance	379	$ 493
Other Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Intangible assets, beginning balance	493	580
Acquisition during period		41
Amortization expense	(114)	(128)	$ (243)
Intangible assets, ending balance	$ 379	$ 493	$ 580