Basis of Presentation - Additional Information (Detail) - USD ($) $ in Thousands			3 Months Ended		9 Months Ended
	Nov. 23, 2016	Nov. 14, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Mar. 31, 2016	Jun. 30, 2015
Company And Summary Of Significant Accounting Policies [Line Items]
Shares issued in connection with acquisition of business, net of issuance costs					$ 4,988
Payment related to acquisition of business, net of cash acquired					16,528	$ 3,908
Common stock issued under public offering, net of issuance costs					503,061
Forward loss related to loss contracts			$ 800	$ 400	$ 2,800	2,100
Defense contract audit agency completed cost audits					Contract costs on U.S. government contracts are subject to audit and review by the Defense Contracting Management Agency (DCMA), the Defense Contract Audit Agency (DCAA), and other U.S. government agencies, as well as negotiations with U.S. government representatives. The Company’s incurred cost audits by the DCAA have not been concluded for fiscal year 2016. As of December 31, 2016, the DCAA had completed its incurred cost audit for fiscal year 2004 and approved the Company’s incurred cost claims for fiscal years 2005 through 2015 without further audit. Although the Company has recorded contract revenues subsequent to fiscal year 2015 based upon an estimate of costs that the Company believes will be approved upon final audit or review, the Company does not know the outcome of any ongoing or future audits or reviews and adjustments, and if future adjustments exceed the Company’s estimates, its profitability would be adversely affected.
Advertising costs			1,900	3,100	$ 3,500	9,700
Capitalized interest expense			13,400	$ 7,700	35,200	20,900
Total capitalized costs related to patents			3,200		3,200		$ 3,200
Total capitalized costs related to orbital slots and other licenses			15,400		15,400		15,400
Accumulated amortization of patents, orbital slots and other licenses			2,000		2,000		1,700
Capitalized debt issuance costs			6,100		$ 6,100
Minimum [Member]
Company And Summary Of Significant Accounting Policies [Line Items]
Property, equipment and satellites, estimated useful life (years)					2 years
Maximum [Member]
Company And Summary Of Significant Accounting Policies [Line Items]
Property, equipment and satellites, estimated useful life (years)					24 years
Property and Equipment, Net [Member]
Company And Summary Of Significant Accounting Policies [Line Items]
Property and equipment			1,179,608		$ 1,179,608		1,050,886
Accumulated depreciation and amortization			633,933		$ 633,933		563,976
CPE Leased Equipment [Member] | Minimum [Member]
Company And Summary Of Significant Accounting Policies [Line Items]
Property, equipment and satellites, estimated useful life (years)					4 years
CPE Leased Equipment [Member] | Maximum [Member]
Company And Summary Of Significant Accounting Policies [Line Items]
Property, equipment and satellites, estimated useful life (years)					5 years
CPE Leased Equipment [Member] | Property and Equipment, Net [Member]
Company And Summary Of Significant Accounting Policies [Line Items]
Property and equipment			268,742		$ 268,742		260,409
Accumulated depreciation and amortization			153,400		$ 153,400		136,400
Common Stock [Member]
Company And Summary Of Significant Accounting Policies [Line Items]
Shares issued in connection with acquisition of business, net of issuance costs					61,888
Common stock issued under public offering, net of issuance costs	7,475,000				7,475,000
Common stock issued under public offering, net of issuance costs					$ 1
Paid-in Capital [Member]
Company And Summary Of Significant Accounting Policies [Line Items]
Shares issued in connection with acquisition of business, net of issuance costs					4,988
Common stock issued under public offering, net of issuance costs	$ 503,100				503,060
Revolving Credit Facility [Member]
Company And Summary Of Significant Accounting Policies [Line Items]
Payments of revolving credit facility borrowings	$ 225,000				270,000	$ 185,000
Engreen [Member]
Company And Summary Of Significant Accounting Policies [Line Items]
Purchase price of the acquisition								$ 5,300
Arconics [Member]
Company And Summary Of Significant Accounting Policies [Line Items]
Purchase price of acquisition of business		$ 21,600
Shares issued in connection with acquisition of business, net of issuance costs		$ 5,000
Shares issued in connection with acquisition of business, net of issuance costs		61,888
Cash consideration related to acquisition of business		$ 16,600
Cash acquired from acquisition of business		600
Payment related to acquisition of business, net of cash acquired		$ 16,000
Unfavorable Regulatory Action [Member]
Company And Summary Of Significant Accounting Policies [Line Items]
U.S. government contract-related reserves			$ 1,700		$ 1,700		$ 2,500