Stockholders' Equity Stockholders' Equity (Schedule of Components of Other Comprehensive Income / (Loss)) (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Tax benefit (expense) recorded in Stockholders' Equity	$ 1,461	$ (1,617)	$ (70)
Tax benefits associated with stock compensation programs	$ 58	$ 48	$ 51