Accumulated Other Comprehensive Income (Loss) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
accumulated other comprehensive income [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (91)	$ (268)
Other Comprehensive Income (Loss), before Tax	34	(31)
Other Comprehensive Income (Loss), Net of Tax	(3)	(11)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	31	(42)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(60)	(310)
Currency Translation [Member]
accumulated other comprehensive income [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	89	(33)
Other Comprehensive Income (Loss), before Tax	26	(2)
Other Comprehensive Income (Loss), Net of Tax	0	0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	26	(2)
Accumulated Other Comprehensive Income (Loss), Net of Tax	115	(35)
Cash Flow Hedges [Member]
accumulated other comprehensive income [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(20)	(2)
Other Comprehensive Income (Loss), before Tax	13	(29)
Other Comprehensive Income (Loss), Net of Tax	0	15
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	13	(44)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(7)	(46)
Postretirement Benefit Plans [Member]
accumulated other comprehensive income [Line Items]
Accumulated Other Comprehensive Income (Loss), Net of Tax	(160)	(233)
Other Comprehensive Income (Loss), before Tax	(5)	0
Other Comprehensive Income (Loss), Net of Tax	3	(4)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent	(8)	4
Accumulated Other Comprehensive Income (Loss), Net of Tax	$ (168)	$ (229)