Changes In Fair Value of Level 3 Financial Assets (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2012	Jun. 30, 2012
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, beginning of the period	$ 78,397	$ 74,596
Calls at par value		(225)
Other than Temporary Impairment Losses, Investments	(1,969)	(1,969)
(Increase) decrease in previously recognized unrealized losses included in other comprehensive income	(2,532)	1,494
Balance, end of the period	$ 73,896	$ 73,896

The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

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