Investments - Additional Information (Detail) (USD $)	Dec. 31, 2014	Dec. 31, 2013
Schedule of Trading Securities and Other Trading Assets [Line Items]
Short-term investments	$ 20,562,000us-gaap_ShortTermInvestments	$ 13,567,000us-gaap_ShortTermInvestments
Time deposits of cash and cash equivalents	2,400,000us-gaap_TimeDepositsAtCarryingValue	5,500,000us-gaap_TimeDepositsAtCarryingValue
FDIC Guaranteed Certificates of Deposit [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Short-term investments	2,100,000
Corporate Notes/Bonds [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Short-term investments	$ 18,500,000

- Definition

Any certificate of deposit or savings account held by a bank or other financial institution for a short-term specified period of time. Because of their short-term, time deposits are considered highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Generally, only investments with original maturities of three months or less qualify under that definition. Original maturity means original maturity to the entity holding the investment. For example, both a three-month US Treasury bill and a three-year Treasury note purchased three months from maturity qualify as cash equivalents. However, a Treasury note purchased three-years ago does not become a cash equivalent when its remaining maturity is three months.

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