Employee Benefits (Details 3) (Qualified Defined Contribution Benefit Plan [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Qualified Defined Contribution Benefit Plan [Member]
Defined Contribution Plan Disclosure [Line Items]
Company common stock included in the assets of the 401(k) Plan (in shares)	8	9
Expenses related to the 401(k) Plan	$ 81	$ 89	$ 76