CONSOLIDATED STATEMENTS OF COMPREHENSIVE (LOSS) INCOME - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Revenue, Net [Abstract]
Service	$ 5,930	$ 6,323	$ 17,968	$ 19,252
Equipment	2,309	2,226	6,355	5,556
Net operating revenues	8,239	8,549	24,323	24,808
Net operating expenses
Cost of Services (exclusive of depreciation and amortization included below)	1,733	1,925	5,140	6,125
Cost of Products (exclusive of depreciation and amortization included below)	1,673	1,985	4,622	5,097
Selling, general and administrative	2,108	2,080	6,059	5,992
Severance and exit costs	13	19	13	30
Depreciation	1,977	1,837	5,693	5,227
Amortization	196	255	628	813
Other, net	(188)	137	(323)	230
Total costs and expenses	7,512	8,238	21,832	23,514
Operating Income	727	311	2,491	1,294
Other (expense) income
Interest Expense	(581)	(619)	(1,789)	(1,864)
Other income, net	(42)	(60)	(50)	(67)
Nonoperating Expense	(623)	(679)	(1,839)	(1,931)
Loss (income) before income taxes	104	(368)	652	(637)
Income tax benefit	7,052	(111)	6,662	(286)
Net (loss) income	7,162	(479)	7,320	(923)
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	7,156	(479)	7,314	(923)
Net Income (Loss) Attributable to Noncontrolling Interest	$ 6	$ 0	$ 6	$ 0
Basic net (loss) income per common share	$ 1.79	$ (0.12)	$ 1.83	$ (0.23)
Diluted net (loss) income per common share	$ 1.76	$ (0.12)	$ 1.79	$ (0.23)
Basic weighted average common shares outstanding	4,001	3,983	3,998	3,979
Diluted weighted average common shares outstanding	4,061	3,983	4,080	3,979
Other comprehensive (loss) income, net of tax:
Net unrealized holding gains on securities and other	$ 7	$ (5)	$ 25	$ 0
Net unrealized holding gains on derivatives	19	0	12	0
Net unrecognized net periodic pension and other postretirement benefits	0	0	1	2
Other comprehensive income	26	(5)	38	2
Comprehensive (loss) income	$ 7,182	$ (484)	$ 7,352	$ (921)