Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended		12 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Mar. 31, 2019
Cash flows from operating activities:
Net income (loss)	$ 8,062		$ (25,598)	$ (1,675)	$ (61,095)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation				135,144	128,990
Amortization of intangible assets				31,206	28,281
Stock-based compensation expense	21,100		19,400	42,328	38,503
Loss on disposition of fixed assets				23,566	26,025
Other non-cash adjustments				(4,023)	(32,753)
Increase (decrease) in cash resulting from changes in operating assets and liabilities, net of effect of acquisition:
Accounts receivable				893	(10,595)
Inventories				(34,091)	(34,173)
Other assets				(6,403)	(9,771)
Accounts payable				5,582	19,908
Accrued liabilities				(2,292)	10,396
Other liabilities				(6,943)	7,576
Net cash provided by operating activities				183,292	111,292
Cash flows from investing activities:
Purchase of property, equipment and satellites				(329,558)	(333,466)
Cash paid for patents, licenses and other assets				(35,445)	(21,692)
Proceeds from insurance claims on ViaSat-2 satellite		$ 2,300		2,277	44,394	$ 185,700
Proceeds from sale of real property					14,034
Payments related to acquisition of business, net of cash acquired					(2,339)
Net cash used in investing activities				(362,726)	(299,069)
Cash flows from financing activities:
Proceeds from debt borrowings					355,000
Payments of debt borrowings				(14,821)	(186,386)
Payment of debt issuance costs				(2,479)
Proceeds from issuance of common stock under equity plans				27,016	11,087
Purchase of common stock in treasury (immediately retired) related to tax withholdings for stock-based compensation				(3,128)	(6,551)
Other financing activities				(1,368)	(3,886)
Net cash provided by financing activities				5,220	169,264
Effect of exchange rate changes on cash				(442)	(1,306)
Net decrease in cash and cash equivalents				(174,656)	(19,819)
Cash and cash equivalents at beginning of period		$ 261,701		261,701	71,446	71,446
Cash and cash equivalents at end of period	$ 87,045		$ 51,627	87,045	51,627	$ 261,701
Non-cash investing and financing activities:
Issuance of common stock in satisfaction of certain accrued employee compensation liabilities				22,829	32,129
Capital expenditures not paid for				$ 4,023	$ 6,724