Stockholders' Equity - Schedule of Other Comprehensive Income (Loss), Net of Tax (Details) - USD ($)	3 Months Ended		9 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Equity [Abstract]
Average cost per share (dollars per share)	$ 140.96	$ 186.99	$ 140.96
Foreign currency translation adjustments
Foreign currency translation adjustments arising during period, net of income tax expense (benefit) of $11, nil, ($1) and nil	$ (398,000,000)	$ (246,000,000)	$ (782,000,000)	$ (142,000,000)
Reclassified to income statement, net of income tax expense of nil, nil nil and nil	0	0	20,000,000	0
Foreign currency translation adjustments	(398,000,000)	(246,000,000)	(762,000,000)	(142,000,000)
Unrealized gains (losses) on cash flow hedges
Unrealized gains (losses) on cash flow hedges arising during period, net of income tax expense of nil, nil, nil and nil	(14,000,000)	(1,000,000)	(20,000,000)	5,000,000
Changes in retirement-related benefit plans
Net actuarial loss and prior service cost arising during the period, net of income tax benefit of nil, nil, nil and $9	0	0	0	(28,000,000)
Amortization of actuarial loss and prior service costs, net of income tax expense of $1, $5, $2 and $9	2,000,000	8,000,000	6,000,000	23,000,000
Foreign currency translation adjustments and other, net of income tax expense of nil, nil, nil and nil	6,000,000	7,000,000	14,000,000	3,000,000
Changes in retirement-related benefit plans	8,000,000	15,000,000	20,000,000	(2,000,000)
Other Comprehensive Income (Loss), Net of Tax	(404,000,000)	(232,000,000)	(762,000,000)	(139,000,000)
Foreign currency translation adjustments arising during period, tax benefit	0	3,000,000	1,000,000	3,000,000
Reclassified to income statement, tax expense	0	0	0	0
Unrealized gains (losses) on cash flow hedges arising during period, tax expense	0	0	0	0
Net actuarial gain (loss) and prior service cost arising during the period, tax benefit	0	0	0	9,000,000
Amortization of actuarial loss and prior service costs, tax expense	1,000,000	4,000,000	3,000,000	13,000,000
Foreign currency translation adjustments, tax expense	$ 0	$ 0	$ 0	$ 0