Other Comprehensive Income (Loss) (Components of Accumulated Other Comprehensive Income Loss) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance as of January 1, 2014	$ (2,621)	$ (3,307)
Other comprehensive loss before reclassifications	(1,331)	491
Amounts reclassified from accumulated other comprehensive loss	105	195
Other comprehensive (loss) income, net of tax	(1,226)	686	(119)
Balance as of December 31, 2014	(3,847)	(2,621)	(3,307)
Foreign currency translation adjustments (net of deferred tax (asset) liability of $(5) and $7 in 2014 and 2013, respectively)	(459)	56
Net unrealized investment gains (net of deferred tax liability of $2 in both 2014 and 2013)	5	5
Net charges related to pension / post-retirement plans (net of deferred tax asset of $1,587 and $1,213 in 2014 and 2013, respectively)	(3,393)	(2,682)
Accumulated other comprehensive income (loss)	(3,847)	(2,621)	(3,307)
Foreign currency translation adjustments, tax portion	(5)	7
Net unrealized investment gains, tax portion	2	2
Net charges related to pension/ retiree plans, tax portion	1,587	1,213
Unrealized Investment Gains [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance as of January 1, 2014	5	4
Other comprehensive loss before reclassifications	0	1
Amounts reclassified from accumulated other comprehensive loss	0	0
Other comprehensive (loss) income, net of tax	0	1
Balance as of December 31, 2014	5	5
Accumulated other comprehensive income (loss)	5	5
Pension/Post-Retirement Plans Gains (Losses) [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance as of January 1, 2014	(2,682)	(3,451)
Other comprehensive loss before reclassifications	(816)	574
Amounts reclassified from accumulated other comprehensive loss	105	195
Other comprehensive (loss) income, net of tax	(711)	769
Balance as of December 31, 2014	(3,393)	(2,682)
Accumulated other comprehensive income (loss)	(3,393)	(2,682)
Foreign Currency Translation Adjustments [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance as of January 1, 2014	56	140
Other comprehensive loss before reclassifications	(515)	(84)
Amounts reclassified from accumulated other comprehensive loss	0	0
Other comprehensive (loss) income, net of tax	(515)	(84)
Balance as of December 31, 2014	(459)	56
Accumulated other comprehensive income (loss)	$ (459)	$ 56