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, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
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
Revenues	7,795,000	8,433,000	15,937,000	16,558,000
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
Selling, general and administrative	1,936,000	1,861,000	3,843,000	3,728,000
Severance and exit costs	19,000		46,000
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
Total other 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
Basic net (loss) income per common share	$ (0.07)	$ 0.05	$ (0.09)	$ 0.09
Diluted net (loss) income per common share	$ (0.07)	$ 0.05	$ (0.09)	$ 0.09
Basic weighted average common shares outstanding	4,098	4,061	4,092	4,036
Diluted weighted average common shares outstanding	4,098	4,124	4,092	4,095
Services [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Service revenue	$ 5,273,000	$ 5,762,000	$ 10,836,000	$ 11,502,000