Acquisitions - Reconciliation of Assets Acquired with Cash Paid at Closing (Detail) - USD ($)		12 Months Ended
	Feb. 27, 2015	Dec. 31, 2015	Jun. 30, 2016
Business Acquisition [Line Items]
Due Nexgen - contingent liability		$ 0	$ 0
Nexgen Wireless, Inc. [Member]
Business Acquisition [Line Items]
Net assets acquired		21,431,000
Due Nexgen - contingent liability	$ (2,250,000)	(91,000)
Due Nexgen - working capital adjustment		(840,000)
Cash paid at closing	$ 18,250,000	$ 20,500,000