Other Financial Data (Changes in Accumulated Other Comprehensive Loss) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance as of December 31, 2013	$ (2,287)
Other comprehensive income (loss) before reclassifications	(721)
Amounts reclassified from accumulated other comprehensive income (loss)	1,153
Total other comprehensive income (loss)	432	1,013	(424)
Balance as of December 31, 2014	(1,855)	(2,287)
Gains and Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance as of December 31, 2013	(1)
Other comprehensive income (loss) before reclassifications	0
Amounts reclassified from accumulated other comprehensive income (loss)	1
Total other comprehensive income (loss)	1
Balance as of December 31, 2014	0
Unrealized Gains and Losses on Available-for-Sale Securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance as of December 31, 2013	(2)
Other comprehensive income (loss) before reclassifications	46
Amounts reclassified from accumulated other comprehensive income (loss)	0
Total other comprehensive income (loss)	46
Balance as of December 31, 2014	44
Retirement Benefit Items
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance as of December 31, 2013	(2,188)
Other comprehensive income (loss) before reclassifications	(718)
Amounts reclassified from accumulated other comprehensive income (loss)	1,211
Total other comprehensive income (loss)	493
Balance as of December 31, 2014	(1,695)
Foreign Currency Translation Adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance as of December 31, 2013	(96)
Other comprehensive income (loss) before reclassifications	(49)
Amounts reclassified from accumulated other comprehensive income (loss)	(59)
Total other comprehensive income (loss)	(108)
Balance as of December 31, 2014	$ (204)