Intangible Assets and Goodwill (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Intangible assets
Weighted Amortizable Life (in years)	14 years		14 years
Gross Carrying Amount	$ 4,290		$ 4,452
Accumulated Amortization	(1,400)		(1,376)
Net	2,890		3,076
Total intangible assets, net	2,890		3,076
Amortization expense	87	92
2015	331
2016	310
2017	308
2018	303
2019	301
Thereafter	1,424
Customer Relationships
Intangible assets
Weighted Amortizable Life (in years)	15 years		15 years
Gross Carrying Amount	2,400		2,489
Accumulated Amortization	(687)		(669)
Net	1,713		1,820
Intellectual Property
Intangible assets
Weighted Amortizable Life (in years)	11 years		11 years
Gross Carrying Amount	1,656		1,724
Accumulated Amortization	(579)		(578)
Net	1,077		1,146
Other
Intangible assets
Weighted Amortizable Life (in years)	11 years		11 years
Gross Carrying Amount	234		239
Accumulated Amortization	(134)		(129)
Net	$ 100		$ 110