Guarantor Financial Information (CONDENSED CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME (LOSS)) (Details) - USD ($) $ in Millions	3 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Condensed Income Statements, Captions [Line Items]
Net operating revenues	$ 8,157	$ 8,012
Cost of Services (exclusive of depreciation and amortization included below)	1,709	2,099
Cost of Products (exclusive of depreciation and amortization included below)	1,545	1,419
Net operating expenses
Selling, general and administrative	1,938	1,917
Severance and exit costs	0	16
Depreciation	1,831	1,680
Amortization	223	287
Other, net	(252)	233
Total costs and expenses	6,994	7,651
Operating Income	1,163	361
Other (expense) income
Interest Income	19	10
Interest Expense	(613)	(615)
(Losses) earnings of Subsidiaries	0	0
Other nonoperating income (expense), excluding interest income	(71)	(2)
Nonoperating Expense	(665)	(607)
Loss (income) before income taxes	498	(246)
Income tax benefit	(292)	(56)
Net (loss) income	206	(302)
Other Comprehensive Income (Loss), Net of Tax	(4)	(1)
Comprehensive (loss) income	202	(303)
Consolidation, Eliminations [Member]
Condensed Income Statements, Captions [Line Items]
Net operating revenues	0	0
Cost of Services (exclusive of depreciation and amortization included below)	0	0
Cost of Products (exclusive of depreciation and amortization included below)	0	0
Net operating expenses
Selling, general and administrative	0	0
Severance and exit costs		0
Depreciation	0	0
Amortization	0	0
Other, net	0	0
Total costs and expenses	0	0
Operating Income	0	0
Other (expense) income
Interest Income	(228)	(219)
Interest Expense	228	219
(Losses) earnings of Subsidiaries	(730)	208
Other nonoperating income (expense), excluding interest income	0	0
Nonoperating Expense	(730)	208
Loss (income) before income taxes	(730)	208
Income tax benefit	0	0
Net (loss) income	(730)	208
Other Comprehensive Income (Loss), Net of Tax	(1)	0
Comprehensive (loss) income	(731)	208
Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Net operating revenues	0	0
Cost of Services (exclusive of depreciation and amortization included below)	0	0
Cost of Products (exclusive of depreciation and amortization included below)	0	0
Net operating expenses
Selling, general and administrative	0	0
Severance and exit costs		0
Depreciation	0	0
Amortization	0	0
Other, net	0	0
Total costs and expenses	0	0
Operating Income	0	0
Other (expense) income
Interest Income	198	198
Interest Expense	(198)	(198)
(Losses) earnings of Subsidiaries	206	(302)
Other nonoperating income (expense), excluding interest income	0	0
Nonoperating Expense	206	(302)
Loss (income) before income taxes	206	(302)
Income tax benefit	0	0
Net (loss) income	206	(302)
Other Comprehensive Income (Loss), Net of Tax	(4)	(1)
Comprehensive (loss) income	202	(303)
Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Net operating revenues	0	0
Cost of Services (exclusive of depreciation and amortization included below)	0	0
Cost of Products (exclusive of depreciation and amortization included below)	0	0
Net operating expenses
Selling, general and administrative	0	0
Severance and exit costs		0
Depreciation	0	0
Amortization	0	0
Other, net	(55)	0
Total costs and expenses	(55)	0
Operating Income	55	0
Other (expense) income
Interest Income	45	28
Interest Expense	(351)	(423)
(Losses) earnings of Subsidiaries	524	94
Other nonoperating income (expense), excluding interest income	(67)	(1)
Nonoperating Expense	151	(302)
Loss (income) before income taxes	206	(302)
Income tax benefit	0	0
Net (loss) income	206	(302)
Other Comprehensive Income (Loss), Net of Tax	(4)	(1)
Comprehensive (loss) income	202	(303)
Non-Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Net operating revenues	8,157	8,012
Cost of Services (exclusive of depreciation and amortization included below)	1,709	2,099
Cost of Products (exclusive of depreciation and amortization included below)	1,545	1,419
Net operating expenses
Selling, general and administrative	1,938	1,917
Severance and exit costs		16
Depreciation	1,831	1,680
Amortization	223	287
Other, net	(197)	233
Total costs and expenses	7,049	7,651
Operating Income	1,108	361
Other (expense) income
Interest Income	4	3
Interest Expense	(292)	(213)
(Losses) earnings of Subsidiaries	0	0
Other nonoperating income (expense), excluding interest income	(4)	(1)
Nonoperating Expense	(292)	(211)
Loss (income) before income taxes	816	150
Income tax benefit	(292)	(56)
Net (loss) income	524	94
Other Comprehensive Income (Loss), Net of Tax	5	1
Comprehensive (loss) income	$ 529	$ 95