Guarantor Financial Information (CONDENSED CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME (LOSS)) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Dec. 31, 2018
Condensed Income Statements, Captions [Line Items]
Severance and exit costs	$ 20,000		$ 66,000
Net operating revenues	8,080,000	$ 8,601,000	24,017,000	$ 25,159,000
Service revenue	8,080,000	8,601,000	24,017,000	25,159,000
Revenue, equipment sales, net	1,372,000	1,589,000	3,784,000	4,180,000
Revenue, equipment rentals, net	1,292,000	1,313,000	3,981,000	3,778,000
Cost of Services (exclusive of depreciation and amortization included below)	1,718,000	1,648,000	5,203,000	5,019,000
Cost of equipment sales	1,646,000	1,734,000	4,346,000	4,521,000
Cost of equipment rentals	201,000	182,000	666,000	457,000
Net operating expenses
Selling, general and administrative	2,045,000	2,003,000	5,888,000	5,731,000
Depreciation, network and other	1,071,000	1,088,000	3,256,000	3,132,000
Depreciation, equipment rentals	1,011,000	1,137,000	3,096,000	3,454,000
Amortization	474,000	145,000	698,000	475,000
Other, net	(152,000)	185,000	106,000	298,000
Total costs and expenses	8,014,000	8,122,000	23,259,000	23,087,000
Operating Income	66,000	479,000	758,000	2,072,000
Other (expense) income
Interest Income	17,000	38,000	63,000	129,000
Interest Expense	(589,000)	(664,000)	(1,802,000)	(1,934,000)
(Losses) earnings of Subsidiaries	0	0	0	0
Other nonoperating income (expense), excluding interest income	(23,000)	(6,000)	(27,000)	24,000
Nonoperating Expense	(595,000)	(632,000)	(1,766,000)	(1,781,000)
Loss (income) before income taxes	(529,000)	(153,000)	(1,008,000)	291,000
Income tax benefit	408,000	8,000	494,000	(56,000)
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(121,000)	(145,000)	(514,000)	235,000
Net Income (Loss) Attributable to Noncontrolling Interest	1,000	4,000	9,000	(4,000)
Net Income (Loss) Attributable to Parent	(120,000)	(141,000)	(505,000)	231,000
Other Comprehensive Income (Loss), Net of Tax	(35,000)	(25,000)	(61,000)	(20,000)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(156,000)	(170,000)	(575,000)	215,000
Impairments	19,000		231,000	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	(834,000)	(904,000)	(2,534,000)	(2,699,000)
Interest Expense	834,000	904,000	2,534,000	2,699,000
(Losses) earnings of Subsidiaries	238,000	210,000	969,000	(568,000)
Other nonoperating income (expense), excluding interest income	0	0	0	0
Nonoperating Expense	238,000	210,000	969,000	(568,000)
Loss (income) before income taxes	238,000	210,000	969,000	(568,000)
Income tax benefit	0	0	0	0
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	238,000	210,000	969,000	(568,000)
Net Income (Loss) Attributable to Noncontrolling Interest	0	0	0	0
Net Income (Loss) Attributable to Parent	238,000	210,000	969,000	(568,000)
Other Comprehensive Income (Loss), Net of Tax	72,000	25,000	97,000	30,000
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	310,000	235,000	1,066,000	(538,000)
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	227,000	227,000	679,000	679,000
Interest Expense	(227,000)	(227,000)	(679,000)	(679,000)
(Losses) earnings of Subsidiaries	(120,000)	(141,000)	(505,000)	231,000
Other nonoperating income (expense), excluding interest income	0	0	0	0
Nonoperating Expense	(120,000)	(141,000)	(505,000)	231,000
Loss (income) before income taxes	(120,000)	(141,000)	(505,000)	231,000
Income tax benefit	0	0	0	0
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(120,000)	(141,000)	(505,000)	231,000
Net Income (Loss) Attributable to Noncontrolling Interest	0	0	0	0
Net Income (Loss) Attributable to Parent	(120,000)	(141,000)	(505,000)	231,000
Other Comprehensive Income (Loss), Net of Tax	(35,000)	(25,000)	(61,000)	(20,000)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(155,000)	(166,000)	(566,000)	211,000
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	511,000	540,000	1,546,000	1,632,000
Interest Expense	(513,000)	(609,000)	(1,585,000)	(1,755,000)
(Losses) earnings of Subsidiaries	(118,000)	(69,000)	(464,000)	337,000
Other nonoperating income (expense), excluding interest income	0	(3,000)	(2,000)	17,000
Nonoperating Expense	(120,000)	(141,000)	(505,000)	231,000
Loss (income) before income taxes	(120,000)	(141,000)	(505,000)	231,000
Income tax benefit	0	0	0	0
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(120,000)	(141,000)	(505,000)	231,000
Net Income (Loss) Attributable to Noncontrolling Interest	0	0	0	0
Net Income (Loss) Attributable to Parent	(120,000)	(141,000)	(505,000)	231,000
Other Comprehensive Income (Loss), Net of Tax	(35,000)	(25,000)	(61,000)	(20,000)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(155,000)	(166,000)	(566,000)	211,000
Non-Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Net operating revenues	8,080,000	8,601,000	24,017,000	25,159,000
Revenue, equipment sales, net	1,372,000	1,589,000	3,784,000	4,180,000
Revenue, equipment rentals, net	1,292,000	1,313,000	3,981,000	3,778,000
Cost of Services (exclusive of depreciation and amortization included below)	1,718,000	1,648,000	5,203,000	5,019,000
Cost of equipment sales	1,646,000	1,734,000	4,346,000	4,521,000
Cost of equipment rentals	201,000	182,000	666,000	457,000
Net operating expenses
Selling, general and administrative	2,045,000	2,003,000	5,888,000	5,731,000
Depreciation, network and other	1,071,000	1,088,000	3,256,000	3,132,000
Depreciation, equipment rentals	1,011,000	1,137,000	3,096,000	3,454,000
Amortization	474,000	145,000	698,000	475,000
Other, net	(152,000)	185,000	106,000	298,000
Total costs and expenses	8,014,000	8,122,000	23,259,000	23,087,000
Operating Income	66,000	479,000	758,000	2,072,000
Other (expense) income
Interest Income	113,000	175,000	372,000	517,000
Interest Expense	(683,000)	(732,000)	(2,072,000)	(2,199,000)
(Losses) earnings of Subsidiaries	0	0	0	0
Other nonoperating income (expense), excluding interest income	(23,000)	(3,000)	(25,000)	7,000
Nonoperating Expense	(593,000)	(560,000)	(1,725,000)	(1,675,000)
Loss (income) before income taxes	(527,000)	(81,000)	(967,000)	397,000
Income tax benefit	408,000	8,000	494,000	(56,000)
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(119,000)	(73,000)	(473,000)	341,000
Net Income (Loss) Attributable to Noncontrolling Interest	1,000	4,000	9,000	(4,000)
Net Income (Loss) Attributable to Parent	(118,000)	(69,000)	(464,000)	337,000
Other Comprehensive Income (Loss), Net of Tax	(37,000)	0	(36,000)	(10,000)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(156,000)	(73,000)	(509,000)	331,000
Services [Member]
Condensed Income Statements, Captions [Line Items]
Service revenue	5,416,000	5,699,000	16,252,000	17,201,000
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	$ 5,416,000	$ 5,699,000	$ 16,252,000	$ 17,201,000