Condensed Consolidated Statement of Cash Flows (Detail) (USD $)	6 Months Ended
	Sep. 28, 2012	Sep. 30, 2011
Cash flows from operating activities:
Net cash provided by (used in) operating activities	$ 42,087,000	$ 23,786,000
Cash flows from investing activities:
Purchase of property, equipment and satellites, net	(74,652,000)	(133,313,000)
Cash paid for patents, licenses and other assets	(12,351,000)	(8,295,000)
Net cash provided by (used in) investing activities	(87,003,000)	(141,608,000)
Cash flows from financing activities:
Proceeds from issuance of common stock under equity plans	14,055,000	6,167,000
Payment of debt issuance costs	(2,215,000)	0
Purchase of common stock in treasury	(2,142,000)	(2,250,000)
Payments on capital lease	(613,000)	(465,000)
Payments of satellite performance incentives obligation	(640,000)
Proceeds from line of credit borrowings		130,000,000
Payments on line of credit		(20,000,000)
Net cash provided by (used in) financing activities	8,445,000	113,452,000
Effect of exchange rate changes on cash	6,000	(113,000)
Net increase (decrease) in cash and cash equivalents	(36,465,000)	(4,483,000)
Cash and cash equivalents at beginning of period	172,583,000	40,490,000
Cash and cash equivalents at end of period	136,118,000	36,007,000
Issuing Parent Company [Member]
Cash flows from operating activities:
Net cash provided by (used in) operating activities	(15,490,000)	(12,993,000)
Cash flows from investing activities:
Purchase of property, equipment and satellites, net	(23,287,000)	(116,927,000)
Cash paid for patents, licenses and other assets	(12,299,000)	(8,277,000)
Long-term intercompany notes and investments	(1,052,000)	3,346,000
Net cash provided by (used in) investing activities	(36,638,000)	(121,858,000)
Cash flows from financing activities:
Proceeds from issuance of common stock under equity plans	14,055,000	6,167,000
Payment of debt issuance costs	(2,215,000)
Purchase of common stock in treasury	(2,142,000)	(2,250,000)
Payments on capital lease	(64,000)	(54,000)
Payments of satellite performance incentives obligation	(640,000)
Proceeds from line of credit borrowings		130,000,000
Payments on line of credit		(20,000,000)
Long-term intercompany financing		20,686,000
Net cash provided by (used in) financing activities	8,994,000	134,549,000
Net increase (decrease) in cash and cash equivalents	(43,134,000)	(302,000)
Cash and cash equivalents at beginning of period	162,426,000	24,347,000
Cash and cash equivalents at end of period	119,292,000	24,045,000
Guarantor Subsidiaries [Member]
Cash flows from operating activities:
Net cash provided by (used in) operating activities	57,710,000	30,987,000
Cash flows from investing activities:
Purchase of property, equipment and satellites, net	(50,689,000)	(16,129,000)
Net cash provided by (used in) investing activities	(50,689,000)	(16,129,000)
Cash flows from financing activities:
Payments on capital lease	(549,000)	(411,000)
Long-term intercompany financing		(20,686,000)
Net cash provided by (used in) financing activities	(549,000)	(21,097,000)
Net increase (decrease) in cash and cash equivalents	6,472,000	(6,239,000)
Cash and cash equivalents at beginning of period	439,000	7,600,000
Cash and cash equivalents at end of period	6,911,000	1,361,000
Non-Guarantor Subsidiaries [Member]
Cash flows from operating activities:
Net cash provided by (used in) operating activities	(133,000)	7,704,000
Cash flows from investing activities:
Purchase of property, equipment and satellites, net	(676,000)	(2,169,000)
Cash paid for patents, licenses and other assets	(52,000)	(18,000)
Net cash provided by (used in) investing activities	(728,000)	(2,187,000)
Cash flows from financing activities:
Long-term intercompany financing	1,052,000	(3,346,000)
Net cash provided by (used in) financing activities	1,052,000	(3,346,000)
Effect of exchange rate changes on cash	6,000	(113,000)
Net increase (decrease) in cash and cash equivalents	197,000	2,058,000
Cash and cash equivalents at beginning of period	9,718,000	8,543,000
Cash and cash equivalents at end of period	9,915,000	10,601,000
Consolidation and Elimination Adjustments [Member]
Cash flows from operating activities:
Net cash provided by (used in) operating activities		(1,912,000)
Cash flows from investing activities:
Purchase of property, equipment and satellites, net		1,912,000
Long-term intercompany notes and investments	1,052,000	(3,346,000)
Net cash provided by (used in) investing activities	1,052,000	(1,434,000)
Cash flows from financing activities:
Long-term intercompany financing	(1,052,000)	3,346,000
Net cash provided by (used in) financing activities	$ (1,052,000)	$ 3,346,000