Intangibles and Other Assets - Schedule of Intangibles and Other Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Intangibles And Other Assets [Abstract]
Purchased patents and other purchased intangible assets	$ 4,605	$ 4,605
Less: Accumulated amortization of purchased patents and other purchased intangibles	(4,605)	(4,599)
Purchased patents and other purchased intangible assets, net	0	6
Other assets	365	258
Intangibles and other assets, net	$ 365	264
Patents, estimated useful lives	10 years
Amortization of intangibles	$ 6	$ 20	$ 67