Marketable Securities Scheduled Maturities of Available-for-Sale Debt Securities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Investments, Debt and Equity Securities [Abstract]
Due within one year, amortized cost	$ 303	$ 306
Due after one year through five years, amortized cost	1,229	1,250
Due after five years through 10 years, amortized cost	100	100
Total, amortized cost	1,632	1,656
Due within one year, fair value	305	307
Due after one year through five years, fair value	1,236	1,264
Due after five years through 10 years, fair value	101	100
Total, fair value	$ 1,642	$ 1,671