New Accounting Pronouncements - Cumulative Effects of Accounting Standards Update on Statement of Comprehensive Income and Balance Sheet (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	3 Months Ended		6 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Service revenue	$ 8,433,000		$ 16,558,000
Revenue, equipment sales, net	1,418,000	$ 994,000	2,591,000	$ 2,181,000
Revenue, equipment rentals, net	1,253,000	966,000	2,465,000	1,865,000
Revenues	8,433,000	7,927,000	16,558,000	16,084,000
Cost of Services (exclusive of depreciation and amortization included below)	1,694,000	1,698,000	3,371,000	3,407,000
Cost of equipment sales	1,517,000	1,404,000	2,787,000	2,949,000
Cost of equipment rentals	151,000	112,000	275,000	224,000
Selling, general and administrative	1,861,000	2,013,000	3,728,000	3,951,000
Severance and exit costs	25,000	0	33,000	0
Depreciation, network and other	1,021,000	997,000	2,044,000	1,974,000
Depreciation, equipment rentals	1,181,000	888,000	2,317,000	1,742,000
Amortization	159,000	209,000	330,000	432,000
Other, net	46,000	5,000	80,000	(359,000)
Total costs and expenses	7,655,000	7,326,000	14,965,000	14,320,000
Operating Income	778,000	601,000	1,593,000	1,764,000
Total other expense	(554,000)	(551,000)	(1,149,000)	(1,216,000)
Loss (income) before income taxes	224,000	50,000	444,000	548,000
Income tax benefit	(17,000)	(98,000)	(64,000)	(390,000)
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	207,000	(48,000)	380,000	158,000
Net Income (Loss) Attributable to Noncontrolling Interest	(11,000)	0	(8,000)	0
Net Income (Loss) Attributable to Parent	$ 196,000	$ (48,000)	$ 372,000	$ 158,000
Basic net (loss) income per common share	$ 0.05	$ (0.01)	$ 0.09	$ 0.04
Diluted net (loss) income per common share	$ 0.05	$ (0.01)	$ 0.09	$ 0.04
Basic weighted average common shares outstanding	4,061	3,998	4,036	3,996
Diluted weighted average common shares outstanding	4,124	3,998	4,095	4,080
Change | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue, equipment sales, net	$ 351,000		$ 632,000
Revenue, equipment rentals, net	(17,000)		(33,000)
Revenues	161,000		283,000
Cost of Services (exclusive of depreciation and amortization included below)	(20,000)		(31,000)
Cost of equipment sales	49,000		71,000
Cost of equipment rentals	0		0
Selling, general and administrative	(93,000)		(174,000)
Severance and exit costs	0		0
Depreciation, network and other	0		0
Depreciation, equipment rentals	0		0
Amortization	0		0
Other, net	0		0
Total costs and expenses	(64,000)		(134,000)
Operating Income	225,000		417,000
Total other expense	0		0
Loss (income) before income taxes	225,000		417,000
Income tax benefit	(47,000)		(87,000)
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	178,000		330,000
Net Income (Loss) Attributable to Noncontrolling Interest	0		0
Net Income (Loss) Attributable to Parent	$ 178,000		$ 330,000
Basic net (loss) income per common share	$ 50,000		$ 80,000
Diluted net (loss) income per common share	$ 50,000		$ 80,000
Basic weighted average common shares outstanding	0		0
Diluted weighted average common shares outstanding	0		0
Balances without adoption of Topic 606
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Revenue, equipment sales, net	$ 1,067,000		$ 1,959,000
Revenue, equipment rentals, net	1,270,000		2,498,000
Revenues	8,272,000		16,275,000
Cost of Services (exclusive of depreciation and amortization included below)	1,714,000		3,402,000
Cost of equipment sales	1,468,000		2,716,000
Cost of equipment rentals	151,000		275,000
Selling, general and administrative	1,954,000		3,902,000
Severance and exit costs	25,000		33,000
Depreciation, network and other	1,021,000		2,044,000
Depreciation, equipment rentals	1,181,000		2,317,000
Amortization	159,000		330,000
Other, net	46,000		80,000
Total costs and expenses	7,719,000		15,099,000
Operating Income	553,000		1,176,000
Total other expense	(554,000)		(1,149,000)
Loss (income) before income taxes	(1,000)		27,000
Income tax benefit	30,000		23,000
Income (Loss) from Continuing Operations, Net of Tax, Including Portion Attributable to Noncontrolling Interest	29,000		50,000
Net Income (Loss) Attributable to Noncontrolling Interest	(11,000)		(8,000)
Net Income (Loss) Attributable to Parent	$ 18,000		$ 42,000
Basic net (loss) income per common share	$ 0		$ 10,000
Diluted net (loss) income per common share	$ 0		$ 10,000
Basic weighted average common shares outstanding	4,061		4,036
Diluted weighted average common shares outstanding	4,124		4,095
Services [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Service revenue	$ 5,762,000	$ 5,967,000	$ 11,502,000	$ 12,038,000
Services [Member] | Change | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Service revenue	(173,000)		(316,000)
Services [Member] | Balances without adoption of Topic 606
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Service revenue	$ 5,935,000		$ 11,818,000