Employee Benefits (Details 3) - 401(k) Defined Contribution Plan - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Contribution Plan Disclosure [Line Items]
Company common stock included in the assets of the 401(k) Plan (in shares)	8	8
Expenses related to the 401(k) Plan	$ 83	$ 81	$ 89