Guarantor Financial Information (CONDENSED CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME (LOSS)) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Condensed Income Statements, Captions [Line Items]
Net operating revenues	$ 8,601,000	$ 8,239,000	$ 25,159,000	$ 24,323,000
Service revenue	8,601,000		25,159,000
Revenue, equipment sales, net	1,589,000	1,262,000	4,180,000	3,443,000
Revenue, equipment rentals, net	1,313,000	1,047,000	3,778,000	2,912,000
Cost of Services (exclusive of depreciation and amortization included below)	1,648,000	1,733,000	5,019,000	5,140,000
Cost of equipment sales	1,734,000	1,673,000	4,521,000	4,622,000
Cost of equipment rentals	182,000	123,000	457,000	347,000
Net operating expenses
Selling, general and administrative	2,003,000	2,108,000	5,731,000	6,059,000
Severance and exit costs	(30,000)		(63,000)	(13,000)
Depreciation, network and other	1,088,000	987,000	3,132,000	2,961,000
Depreciation, equipment rentals	1,137,000	990,000	3,454,000	2,732,000
Amortization	145,000	196,000	475,000	628,000
Other, net	185,000	(298,000)	298,000	(657,000)
Total costs and expenses	8,122,000	7,512,000	23,087,000	21,832,000
Operating Income	479,000	727,000	2,072,000	2,491,000
Other (expense) income
Interest Income	38,000	14,000	129,000	66,000
Interest Expense	(664,000)	(581,000)	(1,934,000)	(1,789,000)
(Losses) earnings of Subsidiaries	0	0	0	0
Other nonoperating income (expense), excluding interest income	(6,000)	(56,000)	24,000	(116,000)
Nonoperating Expense	(632,000)	(623,000)	(1,781,000)	(1,839,000)
Loss (income) before income taxes	(153,000)	104,000	291,000	652,000
Income tax benefit	8,000	7,052,000	(56,000)	6,662,000
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(145,000)	7,156,000	235,000	7,314,000
Net Income (Loss) Attributable to Noncontrolling Interest	4,000	6,000	(4,000)	6,000
Net Income (Loss) Attributable to Parent	(141,000)	7,162,000	231,000	7,320,000
Other Comprehensive Income (Loss), Net of Tax	(25,000)	26,000	(20,000)	38,000
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(170,000)	7,182,000	215,000	7,352,000
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	(904,000)	(643,000)	(2,699,000)	(1,320,000)
Interest Expense	904,000	643,000	2,699,000	1,320,000
(Losses) earnings of Subsidiaries	210,000	(14,250,000)	(568,000)	(15,042,000)
Other nonoperating income (expense), excluding interest income	0	0	0	0
Nonoperating Expense	210,000	(14,250,000)	(568,000)	(15,042,000)
Loss (income) before income taxes	210,000	(14,250,000)	(568,000)	(15,042,000)
Income tax benefit	0	0	0	0
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	210,000	(14,250,000)	(568,000)	(15,042,000)
Net Income (Loss) Attributable to Noncontrolling Interest	0	0	0	0
Net Income (Loss) Attributable to Parent	210,000	(14,250,000)	(568,000)	(15,042,000)
Other Comprehensive Income (Loss), Net of Tax	25,000	(32,000)	30,000	(56,000)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	235,000	(14,282,000)	(538,000)	(15,098,000)
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	198,000	679,000	593,000
Interest Expense	(227,000)	(198,000)	(679,000)	(593,000)
(Losses) earnings of Subsidiaries	(141,000)	7,162,000	231,000	7,320,000
Other nonoperating income (expense), excluding interest income	0	0	0	0
Nonoperating Expense	(141,000)	7,162,000	231,000	7,320,000
Loss (income) before income taxes	(141,000)	7,162,000	231,000	7,320,000
Income tax benefit	0	0	0	0
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(141,000)	7,162,000	231,000	7,320,000
Net Income (Loss) Attributable to Noncontrolling Interest	0	0	0	0
Net Income (Loss) Attributable to Parent	(141,000)	7,162,000	231,000	7,320,000
Other Comprehensive Income (Loss), Net of Tax	(25,000)	26,000	(20,000)	38,000
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(166,000)	7,188,000	211,000	7,358,000
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	(55,000)
Total costs and expenses	0	0	0	(55,000)
Operating Income	0	0	0	55,000
Other (expense) income
Interest Income	540,000	458,000	1,632,000	783,000
Interest Expense	(609,000)	(382,000)	(1,755,000)	(1,171,000)
(Losses) earnings of Subsidiaries	(69,000)	7,088,000	337,000	7,722,000
Other nonoperating income (expense), excluding interest income	(3,000)	(2,000)	17,000	(69,000)
Nonoperating Expense	(141,000)	7,162,000	231,000	7,265,000
Loss (income) before income taxes	(141,000)	7,162,000	231,000	7,320,000
Income tax benefit	0	0	0	0
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(141,000)	7,162,000	231,000	7,320,000
Net Income (Loss) Attributable to Noncontrolling Interest	0	0	0	0
Net Income (Loss) Attributable to Parent	(141,000)	7,162,000	231,000	7,320,000
Other Comprehensive Income (Loss), Net of Tax	(25,000)	26,000	(20,000)	38,000
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(166,000)	7,188,000	211,000	7,358,000
Non-Guarantor Subsidiaries [Member]
Condensed Income Statements, Captions [Line Items]
Net operating revenues	8,601,000	8,239,000	25,159,000	24,323,000
Revenue, equipment sales, net	1,589,000	1,262,000	4,180,000	3,443,000
Revenue, equipment rentals, net	1,313,000	1,047,000	3,778,000	2,912,000
Cost of Services (exclusive of depreciation and amortization included below)	1,648,000	1,733,000	5,019,000	5,140,000
Cost of equipment sales	1,734,000	1,673,000	4,521,000	4,622,000
Cost of equipment rentals	182,000	123,000	457,000	347,000
Net operating expenses
Selling, general and administrative	2,003,000	2,108,000	5,731,000	6,059,000
Depreciation, network and other	1,088,000	987,000	3,132,000	2,961,000
Depreciation, equipment rentals	1,137,000	990,000	3,454,000	2,732,000
Amortization	145,000	196,000	475,000	628,000
Other, net	185,000	(298,000)	298,000	(602,000)
Total costs and expenses	8,122,000	7,512,000	23,087,000	21,887,000
Operating Income	479,000	727,000	2,072,000	2,436,000
Other (expense) income
Interest Income	175,000	1,000	517,000	10,000
Interest Expense	(732,000)	(644,000)	(2,199,000)	(1,345,000)
(Losses) earnings of Subsidiaries	0	0	0	0
Other nonoperating income (expense), excluding interest income	(3,000)	(54,000)	7,000	(47,000)
Nonoperating Expense	(560,000)	(697,000)	(1,675,000)	(1,382,000)
Loss (income) before income taxes	(81,000)	30,000	397,000	1,054,000
Income tax benefit	8,000	7,052,000	(56,000)	6,662,000
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	(73,000)	7,082,000	341,000	7,716,000
Net Income (Loss) Attributable to Noncontrolling Interest	4,000	6,000	(4,000)	6,000
Net Income (Loss) Attributable to Parent	(69,000)	7,088,000	337,000	7,722,000
Other Comprehensive Income (Loss), Net of Tax	0	6,000	(10,000)	18,000
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest	(73,000)	7,088,000	331,000	7,734,000
Services [Member]
Condensed Income Statements, Captions [Line Items]
Service revenue	5,699,000	5,930,000	17,201,000	17,968,000
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	$ 5,699,000	$ 5,930,000	$ 17,201,000	$ 17,968,000