Summary of Changes in Investment in RealD (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013
Schedule of Equity Method Investments [Line Items]
Investment in marketable securities - RealD, Beginning Balance	$ 13,707
Unrealized holding gain	2,189
Investment in marketable securities - RealD, Ending Balance	$ 15,896

- Definition

The aggregate net change in the difference between the fair value and the carrying value, or in the comparative fair values, of marketable securities categorized as trading held at each balance sheet date, that was included in earnings for the period, which may have arisen from (a) securities classified as trading, (b) the unrealized holding gain (loss) on held-to-maturity securities transferred to the trading security category, and (c) the cumulative unrealized gain (loss) which was included in other comprehensive income (a separate component of shareholders' equity) on available-for-sale securities transferred to trading securities during the period.

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