Scheduled Maturities of Available-for-Sale Debt Securities (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Investments, Debt and Equity Securities [Abstract]
Due within one year, amortized cost	$ 615	$ 658
Due after one year through five years, amortized cost	799	1,415
Due after five years through 10 years, amortized cost	207	347
Total, amortized cost	1,621	2,420
Due within one year, fair value	616	659
Due after one year through five years, fair value	810	1,437
Due after five years through 10 years, fair value	207	346
Total, fair value	$ 1,633	$ 2,442