Commitments and Contingencies (Details) (USD $)	12 Months Ended
Jul. 31, 2011	Jul. 31, 2010	Jul. 31, 2009
2012	$ 30,057,000
2013	3,369,000
2014	2,682,000
2015	2,502,000
2016	3,245,000
Thereafter	5,328,000
Total	47,183,000
Lease Expense Charged to Operations	6,891,000	7,665,000	7,491,000
Related party lease payments made	621,000
Original Lease Expiration Date	December 2011
New Lease Expiration Date	December 2021
Additional term of related party lease agreement as an option to exercise (in years)	10
Rent amount in next calendar year for related party lease agreement	580,000
Mobile Data Communications Segment [Member]
Satellite Lease Expenditures Incurred	46,356,000	35,928,000	32,337,000
Total orders received from U.S. government related to BFT-1 contract	$ 343,921,000

Additional term of related party lease agreement as an option to exercise in years.

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The date upon which a lease was originally set to expire.

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Rent amount in next calendar year for related party lease agreement.

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The aggregate amount of orders received from U.S. government related to BFT-1 contract as of the reporting date.

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- Definition

Costs incurred and are directly related to generating revenues from leased and rented property or equipment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.2(c))
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The date upon which a lease or a group of leases is set to expire.

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- Definition

The total of future contractually required payments on leases defined as operating.

+ References

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-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
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-Paragraph 122
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For leases having an initial or remaining non-cancelable letter-terms in excess of one year, required rental payments due within one year of the balance sheet date relating to leases defined as operating.

+ References

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For leases having an initial or remaining non-cancelable letter-terms in excess of one year, required rental payments due within the fifth year of the balance sheet date relating to leases defined as operating.

+ References

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For leases having an initial or remaining non-cancelable letter-terms in excess of one year, required rental payments due within the fourth year of the balance sheet date relating to leases defined as operating.

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For leases having an initial or remaining non-cancelable letter-terms in excess of one year, required rental payments due within the third year of the balance sheet date relating to leases defined as operating.

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For leases having an initial or remaining non-cancelable letter-terms in excess of one year, required rental payments due within the second year of the balance sheet date relating to leases defined as operating.

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For leases having an initial or remaining non-cancelable letter-terms in excess of one year, required rental payments due after the fifth year from the balance sheet date on leases defined as operating.

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Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income.

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Amount of transactions with related party during the financial reporting period.

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