Fair Value Measurements (Detail) - Summary of Marketable Securities Measured at Fair Value (USD $)	3 Months Ended
Mar. 31, 2013
Balance	$ 1,540,000
Increase in fair value of investment	100,000
Balance	$ 1,640,000

- Definition

Amount of increase (decrease) of assets measured at fair value on a recurring basis using unobservable inputs (level 3). Such increase (decrease) may be comprised of changes in fair value (gains or losses) whether realized or unrealized that have been included in earnings, changed net asset value, or other comprehensive income (a separate component of shareholders' equity); purchases, sales, issues, or settlements of assets; and net transfers in to or out of this category within the fair value hierarchy.

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