Financial Instruments Measured at Fair Value on Recurring Basis (Detail) (Fair Value, Measurements, Recurring, USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale securities, debt securities	$ 29,013	$ 32,417
Available-for-sale securities, equity securities	12	11
Fair value of asset	29,025	32,428
Fair Value, Inputs, Level 1
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale securities, debt securities	12,092	17,186
Available-for-sale securities, equity securities	0	0
Fair value of asset	12,092	17,186
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale securities, debt securities	4,485	4,727
Available-for-sale securities, equity securities	12	11
Fair value of asset	4,497	4,738
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Available-for-sale securities, debt securities	12,436	10,504
Available-for-sale securities, equity securities	0	0
Fair value of asset	$ 12,436	$ 10,504

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

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+ Details

- Definition

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

+ References

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+ Details

- Definition

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents investment securities as of the balance sheet date which may include marketable securities, derivative financial instruments, and investments accounted for under the equity method.

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