Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended
	May. 31, 2013	Jun. 30, 2015	Apr. 03, 2015
Unfavorable Regulatory Action [Member]
Loss Contingencies [Line Items]
Total U.S. government contract-related reserves balance		$ 4.0	$ 4.3
Construction in progress [Member] | Property Plant and Equipment - Satellites [Member]
Loss Contingencies [Line Items]
Purchase price under agreement	$ 358.0