Summary of Available-for-Sale Marketable Securities (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized cost, Total	$ 65,434	$ 68,554
Gross unrealized gains, Total	155	140
Gross unrealized losses, Total	(251)	(230)
Fair value, Total	65,338	68,464
Corporate bonds
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale - matures within one year, Amortized cost	3,549	2,852
Available-for-sale - matures after one year through three years, Amortized cost	61,885	65,702
Available-for-sale - matures within one year, Gross unrealized gains	15	6
Available-for-sale - matures after one year through three years, Gross unrealized gains	140	134
Available-for-sale - matures within one year, Gross unrealized losses	(4)	(3)
Available-for-sale - matures after one year through three years, Gross unrealized losses	(247)	(227)
Available-for-sale - matures within one year, Fair value	3,560	2,855
Available-for-sale - matures after one year through three years, Fair value	$ 61,778	$ 65,609