Short-Term Investments - Maturities of Short-Term Investments (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Investments, Debt and Equity Securities [Abstract]
Less than one year	$ 55,278	$ 76,779
Due in 1 - 2 years	24,974	27,727
Total short-term investments, Estimated Fair Value	$ 80,252	$ 104,506

Amount of debt securities categorized neither as held-to-maturity nor trading.

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