Guarantor Financial Information (CONDENSED CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME (LOSS)) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Condensed Income Statements, Captions [Line Items]
Severance and exit costs	$ 19,000		$ 46,000
Net operating revenues	7,795,000	$ 8,433,000	15,937,000	$ 16,558,000
Service revenue	7,795,000	8,433,000	15,937,000	16,558,000
Revenue, equipment sales, net	1,192,000	1,418,000	2,412,000	2,591,000
Revenue, equipment rentals, net	1,330,000	1,253,000	2,689,000	2,465,000
Cost of Services (exclusive of depreciation and amortization included below)	1,775,000	1,694,000	3,485,000	3,371,000
Cost of equipment sales	1,359,000	1,517,000	2,700,000	2,787,000
Cost of equipment rentals	240,000	151,000	465,000	275,000
Net operating expenses
Selling, general and administrative	1,936,000	1,861,000	3,843,000	3,728,000
Depreciation, network and other	1,065,000	1,021,000	2,185,000	2,044,000
Depreciation, equipment rentals	1,056,000	1,181,000	2,085,000	2,317,000
Amortization	106,000	159,000	224,000	330,000
Other, net	21,000	71,000	258,000	113,000
Total costs and expenses	7,558,000	7,655,000	15,245,000	14,965,000
Operating Income	237,000	778,000	692,000	1,593,000
Other (expense) income
Interest Income	16,000	49,000	46,000	91,000
Interest Expense	(594,000)	(633,000)	(1,213,000)	(1,270,000)
(Losses) earnings of Subsidiaries	0	0	0	0
Other nonoperating income (expense), excluding interest income	(2,000)	30,000	(4,000)	30,000
Nonoperating Expense	(580,000)	(554,000)	(1,171,000)	(1,149,000)
Loss (income) before income taxes	(343,000)	224,000	(479,000)	444,000
Income tax benefit	64,000	(17,000)	86,000	(64,000)
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(279,000)	207,000	(393,000)	380,000
Net Income (Loss) Attributable to Noncontrolling Interest	5,000	(11,000)	8,000	(8,000)
Net Income (Loss) Attributable to Parent	(274,000)	196,000	(385,000)	372,000
Other Comprehensive Income (Loss), Net of Tax	(4,000)	9,000	(26,000)	5,000
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(283,000)	216,000	(419,000)	385,000
Impairments	2,000		212,000	0
Consolidation, Eliminations [Member]
Condensed Income Statements, Captions [Line Items]
Net operating revenues	0	0	0	0
Revenue, equipment sales, net	0	0	0	0
Revenue, equipment rentals, net	0	0	0	0
Cost of Services (exclusive of depreciation and amortization included below)	0	0	0	0
Cost of equipment sales	0	0	0	0
Cost of equipment rentals	0	0	0	0
Net operating expenses
Selling, general and administrative	0	0	0	0
Depreciation, network and other	0	0	0	0
Depreciation, equipment rentals	0	0	0	0
Amortization	0	0	0	0
Other, net	0	0	0	0
Total costs and expenses	0	0	0	0
Operating Income	0	0	0	0
Other (expense) income
Interest Income	(837,000)	(1,062,000)	(1,700,000)	(1,795,000)
Interest Expense	837,000	1,062,000	1,700,000	1,795,000
(Losses) earnings of Subsidiaries	534,000	(463,000)	731,000	(841,000)
Other nonoperating income (expense), excluding interest income	0	0	0	0
Nonoperating Expense	534,000	(463,000)	731,000	(841,000)
Loss (income) before income taxes	534,000	(463,000)	731,000	(841,000)
Income tax benefit	0	0	0	0
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	534,000	(463,000)	731,000	(841,000)
Net Income (Loss) Attributable to Noncontrolling Interest	0	0	0	0
Net Income (Loss) Attributable to Parent	534,000	(463,000)	731,000	(841,000)
Other Comprehensive Income (Loss), Net of Tax	3,000	(12,000)	25,000	5,000
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	537,000	(475,000)	756,000	(836,000)
Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Net operating revenues	0	0	0	0
Revenue, equipment sales, net	0	0	0	0
Revenue, equipment rentals, net	0	0	0	0
Cost of Services (exclusive of depreciation and amortization included below)	0	0	0	0
Cost of equipment sales	0	0	0	0
Cost of equipment rentals	0	0	0	0
Net operating expenses
Selling, general and administrative	0	0	0	0
Depreciation, network and other	0	0	0	0
Depreciation, equipment rentals	0	0	0	0
Amortization	0	0	0	0
Other, net	0	0	0	0
Total costs and expenses	0	0	0	0
Operating Income	0	0	0	0
Other (expense) income
Interest Income	226,000	226,000	452,000	452,000
Interest Expense	(226,000)	(226,000)	(452,000)	(452,000)
(Losses) earnings of Subsidiaries	(274,000)	196,000	(385,000)	372,000
Other nonoperating income (expense), excluding interest income	0	0	0	0
Nonoperating Expense	(274,000)	196,000	(385,000)	372,000
Loss (income) before income taxes	(274,000)	196,000	(385,000)	372,000
Income tax benefit	0	0	0	0
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(274,000)	196,000	(385,000)	372,000
Net Income (Loss) Attributable to Noncontrolling Interest	0	0	0	0
Net Income (Loss) Attributable to Parent	(274,000)	196,000	(385,000)	372,000
Other Comprehensive Income (Loss), Net of Tax	(4,000)	9,000	(26,000)	5,000
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(278,000)	205,000	(411,000)	377,000
Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Net operating revenues	0	0	0	0
Revenue, equipment sales, net	0	0	0	0
Revenue, equipment rentals, net	0	0	0	0
Cost of Services (exclusive of depreciation and amortization included below)	0	0	0	0
Cost of equipment sales	0	0	0	0
Cost of equipment rentals	0	0	0	0
Net operating expenses
Selling, general and administrative	0	0	0	0
Depreciation, network and other	0	0	0	0
Depreciation, equipment rentals	0	0	0	0
Amortization	0	0	0	0
Other, net	0	0	0	0
Total costs and expenses	0	0	0	0
Operating Income	0	0	0	0
Other (expense) income
Interest Income	509,000	545,000	1,035,000	1,092,000
Interest Expense	(522,000)	(638,000)	(1,072,000)	(1,209,000)
(Losses) earnings of Subsidiaries	(260,000)	267,000	(346,000)	469,000
Other nonoperating income (expense), excluding interest income	(1,000)	22,000	(2,000)	20,000
Nonoperating Expense	(274,000)	196,000	(385,000)	372,000
Loss (income) before income taxes	(274,000)	196,000	(385,000)	372,000
Income tax benefit	0	0	0	0
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(274,000)	196,000	(385,000)	372,000
Net Income (Loss) Attributable to Noncontrolling Interest	0	0	0	0
Net Income (Loss) Attributable to Parent	(274,000)	196,000	(385,000)	372,000
Other Comprehensive Income (Loss), Net of Tax	(4,000)	9,000	(26,000)	5,000
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(278,000)	205,000	(411,000)	377,000
Non-Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Net operating revenues	7,795,000	8,433,000	15,937,000	16,558,000
Revenue, equipment sales, net	1,192,000	1,418,000	2,412,000	2,591,000
Revenue, equipment rentals, net	1,330,000	1,253,000	2,689,000	2,465,000
Cost of Services (exclusive of depreciation and amortization included below)	1,775,000	1,694,000	3,485,000	3,371,000
Cost of equipment sales	1,359,000	1,517,000	2,700,000	2,787,000
Cost of equipment rentals	240,000	151,000	465,000	275,000
Net operating expenses
Selling, general and administrative	1,936,000	1,861,000	3,843,000	3,728,000
Depreciation, network and other	1,065,000	1,021,000	2,185,000	2,044,000
Depreciation, equipment rentals	1,056,000	1,181,000	2,085,000	2,317,000
Amortization	106,000	159,000	224,000	330,000
Other, net	21,000	71,000	258,000	113,000
Total costs and expenses	7,558,000	7,655,000	15,245,000	14,965,000
Operating Income	237,000	778,000	692,000	1,593,000
Other (expense) income
Interest Income	118,000	340,000	259,000	342,000
Interest Expense	(683,000)	(831,000)	(1,389,000)	(1,404,000)
(Losses) earnings of Subsidiaries	0	0	0	0
Other nonoperating income (expense), excluding interest income	(1,000)	8,000	(2,000)	10,000
Nonoperating Expense	(566,000)	(483,000)	(1,132,000)	(1,052,000)
Loss (income) before income taxes	(329,000)	295,000	(440,000)	541,000
Income tax benefit	64,000	(17,000)	86,000	(64,000)
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(265,000)	278,000	(354,000)	477,000
Net Income (Loss) Attributable to Noncontrolling Interest	5,000	(11,000)	8,000	(8,000)
Net Income (Loss) Attributable to Parent	(260,000)	267,000	(346,000)	469,000
Other Comprehensive Income (Loss), Net of Tax	1,000	3,000	1,000	(10,000)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(264,000)	281,000	(353,000)	467,000
Services [Member]
Condensed Income Statements, Captions [Line Items]
Service revenue	5,273,000	5,762,000	10,836,000	11,502,000
Services [Member] | Consolidation, Eliminations [Member]
Condensed Income Statements, Captions [Line Items]
Service revenue	0	0	0	0
Services [Member] | Parent Company [Member]
Condensed Income Statements, Captions [Line Items]
Service revenue	0	0	0	0
Services [Member] | Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Service revenue	0	0	0	0
Services [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Service revenue	$ 5,273,000	$ 5,762,000	$ 10,836,000	$ 11,502,000