Contractual Maturities of Available-For-Sale Marketable Securities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities
Available for sale securities, Cost	$ 663,625	$ 178,625
Due In One Year Or Less
Schedule of Available-for-sale Securities
Available for sale securities, Cost	431,324
Available for sale securities, Fair Market Value	431,516
Due After One Year Through Five Years
Schedule of Available-for-sale Securities
Available for sale securities, Cost	208,754
Available for sale securities, Fair Market Value	209,902
Due After Five Years Through Ten Years
Schedule of Available-for-sale Securities
Available for sale securities, Cost	7,493
Available for sale securities, Fair Market Value	7,773
Due After Ten Years
Schedule of Available-for-sale Securities
Available for sale securities, Cost	16,054
Available for sale securities, Fair Market Value	18,197
Available-for-sale Securities
Schedule of Available-for-sale Securities
Available for sale securities, Cost	663,625
Available for sale securities, Fair Market Value	$ 667,388

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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+ Details

- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References+ Details