INVESTMENTS (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Held to Maturity and Available-for-sale
Held to maturity and available-for-sale securities, Amortized Cost	$ 492,832	$ 395,855
Held to maturity and available-for-sale securities, Gross Unrealized Holding Gains	100	48
Held to maturity and available-for-sale securities, Fair Value	492,932	395,903
Held to Maturity, Available-for-sale, and Trading
Total Fair Value	505,751	412,087
Auction rate securities
Trading
Fair Value	12,800
Short-term \| Certificates of deposit
Held-to-Maturity
Amortized Cost	6,007	22,045
Fair Value	6,007	22,045
Short-term \| Commercial paper
Held-to-Maturity
Amortized Cost	9,996	5,991
Fair Value	9,996	5,991
Short-term \| Municipal securities
Held-to-Maturity
Amortized Cost	431,597	367,819
Gross Unrealized Holding Gains	76	48
Fair Value	431,673	367,867
Short-term \| Auction rate securities
Trading
Fair Value	6,369	6,392
Long-term \| Municipal securities
Held-to-Maturity
Amortized Cost	45,232
Gross Unrealized Holding Gains	24
Fair Value	45,256
Long-term \| Auction rate securities
Trading
Fair Value	$ 6,450	$ 9,792

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Represents the cost of debt and equity securities, which are categorized as held-to-maturity and available-for-sale, 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

No definition available.

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- Definition

Represents investments in debt securities which are categorized as held-to-maturity and available-for-sale; such investments are normally measured at amortized cost (carrying value) unless circumstances indicate that the value to be recovered from the investment is less than its carried amount. This element may be used in connection with the fair value disclosures required in footnote disclosures to the financial statements.

+ References

No definition available.

+ Details

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- Definition

Represents the gross unrealized gains for securities, at a point in time, which are categorized as held-to-maturity and available-for-sale securities.

+ References

No definition available.

+ Details

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- Definition

Amount of accumulated unrealized gain on investments in debt securities classified as held-to-maturity.

+ References

No definition available.

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- Definition

Amount before other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

+ References

No definition available.

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- Definition

Fair value of investments in debt securities classified as held-to-maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 5

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- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Available-for-Sale Securities

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- Definition

Amount of investments in debt and equity securities and other forms of securities that provide ownership interests classified as trading.

+ References

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