Restructuring and Impairment (Restructuring Liability) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2015	Mar. 31, 2014	Mar. 31, 2013
Restructuring Reserve [Roll Forward]
Balance as of beginning of period				$ 47				$ 33	$ 47	$ 33	$ 28
Expenses									30	48	40
Other restructuring charges									5	3	5
Expenses									35	51	45
Other impairments									2	24	2
Total restructuring and impairments, net	(1)	25	7	6	29	19	18	9	37	75	47
Cash payments									(32)	(34)	(34)
Foreign currency translation and other									(13)		(1)
Balance as of end of period	$ 32				$ 47				$ 32	$ 47	$ 33