Marketable Securities Scheduled Maturities of Available-for-Sale Debt Securities (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Due within one year, amortized cost	$ 101	$ 204
Due after one year through five years, amortized cost	1,422	1,537
Due after five years through 10 years, amortized cost	237	0
Total, amortized cost	1,760	1,741
Due within one year, fair value	101	204
Due after one year through five years, fair value	1,442	1,545
Due after five years through 10 years, fair value	238	0
Total, fair value	$ 1,781	$ 1,749