Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net income	$ 7,760	$ 10,590	$ 2,624	$ 8,915
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation			241,935	207,950
Amortization of intangible assets			50,181	47,159
Stock-based compensation expense	21,700	21,900	64,967	64,236
Loss on disposition of fixed assets			29,841	33,578
Other non-cash adjustments			3,611	(9,394)
Increase (decrease) in cash resulting from changes in operating assets and liabilities:
Accounts receivable			123,374	(23,596)
Inventories			(39,988)	(47,897)
Other assets			24,017	4,075
Accounts payable			(39,004)	8,384
Accrued liabilities			102,603	16,596
Other liabilities			(6,787)	(16,644)
Net cash provided by operating activities			557,374	293,362
Cash flows from investing activities:
Purchase of property, equipment and satellites			(655,672)	(548,225)
Cash paid for patents, licenses and other assets			(47,164)	(49,613)
Proceeds from insurance claims on ViaSat-2 satellite				2,277	$ 188,000	$ 188,000
Net cash used in investing activities			(702,836)	(595,561)
Cash flows from financing activities:
Proceeds from debt borrowings			400,000	110,000
Payments of debt borrowings			(414,604)	(27,142)
Payment of debt issuance costs			(5,060)	(2,479)
Proceeds from issuance of common stock under equity plans			19,101	38,093
Purchase of common stock in treasury (immediately retired) related to tax withholdings for stock-based compensation			(13,013)	(28,268)
Proceeds from common stock issued in private placement, net of issuance costs			174,749
Other financing activities			(4,280)	(1,746)
Net cash provided by financing activities			156,893	88,458
Effect of exchange rate changes on cash			1,604	(182)
Net increase (decrease) in cash and cash equivalents			13,035	(213,923)
Cash and cash equivalents at beginning of period			304,309	261,701	261,701
Cash and cash equivalents at end of period	$ 317,344	$ 47,778	317,344	47,778	$ 304,309	$ 261,701
Non-cash investing and financing activities:
Right-of-use assets obtained in exchange for operating lease liabilities			55,717	17,900
Right-of-use assets obtained in exchange for finance lease liabilities			$ 1,931	$ 72,711