Summary of Restructuring Activity (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended			12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013		Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Beginning Balance				$ 1,591		$ 441		$ 1,043
Cash payments				(476)		(441)		(602)
Restructuring Reserve, Ending Balance		1,591		1,179		1,591		441
Restructuring costs	200	1,700		192		1,731
Other				(128)		(140)
Personnel and Facilities | Antenna Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring Reserve, Beginning Balance				1,591	[1]
Cash payments				(476)	[1]
Restructuring Reserve, Ending Balance		1,591	[1]	1,179	[1]	1,591	[1]
Restructuring costs				192	[1]	1,731	[1]
Other				$ (128)	[1]	$ (140)	[1]

[1] Includes $34 thousand of severance and related benefit costs for the reduction of six personnel in redundant roles that was paid by the end of the second quarter of 2014.