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FAIR VALUE (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Unobservable inputs assets (level 3) [Roll forward]
Beginning balance	$ 11,036	$ 16,049	$ 15,507	$ 17,151	$ 17,151
Change in unrealized gain (loss) included in accumulated other comprehensive loss	46	8	275	256
Settlements	0	(550)	(4,700)	(1,900)
Ending balance	11,082	$ 15,507	11,082	15,507	15,507
Temporary impairment of the auction rates security investments, net of unrealized gain	(160)		(160)		(435)
Fair Value, Measurements, Recurring [Member]
Assets:
Total assets measured at fair value	533,181		533,181		437,325
Fair Value, Measurements, Recurring [Member] | Cash [Member]
Assets:
Total assets measured at fair value	338,510		338,510		405,597
Fair Value, Measurements, Recurring [Member] | Money Market Funds [Member]
Assets:
Total assets measured at fair value	175,328		175,328		5,043
Fair Value, Measurements, Recurring [Member] | Commercial Paper [Member]
Assets:
Total assets measured at fair value	8,261		8,261		11,178
Fair Value, Measurements, Recurring [Member] | Auction Rate Securities [Member]
Assets:
Total assets measured at fair value	11,082		11,082		15,507
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Assets:
Total assets measured at fair value	522,099		522,099		421,818
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Cash [Member]
Assets:
Total assets measured at fair value	338,510		338,510		405,597
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
Assets:
Total assets measured at fair value	175,328		175,328		5,043
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Commercial Paper [Member]
Assets:
Total assets measured at fair value	8,261		8,261		11,178
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Auction Rate Securities [Member]
Assets:
Total assets measured at fair value	0		0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Assets:
Total assets measured at fair value	0		0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Cash [Member]
Assets:
Total assets measured at fair value	0		0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Money Market Funds [Member]
Assets:
Total assets measured at fair value	0		0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Commercial Paper [Member]
Assets:
Total assets measured at fair value	0		0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Auction Rate Securities [Member]
Assets:
Total assets measured at fair value	0		0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member]
Assets:
Total assets measured at fair value	11,082		11,082		15,507
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Cash [Member]
Assets:
Total assets measured at fair value	0		0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Money Market Funds [Member]
Assets:
Total assets measured at fair value	0		0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Commercial Paper [Member]
Assets:
Total assets measured at fair value	0		0		0
Fair Value, Measurements, Recurring [Member] | Fair Value, Inputs, Level 3 [Member] | Auction Rate Securities [Member]
Assets:
Total assets measured at fair value	11,082		11,082		15,507
Auction Rate Securities [Member]
Unobservable inputs assets (level 3) [Roll forward]
Beginning balance			15,507	$ 17,151	17,151
Change in unrealized gain (loss) included in accumulated other comprehensive loss			275		256
Settlements			(4,700)		(1,900)
Ending balance	11,082		$ 11,082		$ 15,507
Auction rate securities variable rate debt instruments interest rate reset period			28 days
The minimum contractual maturities on underlying securities involved in auction rate securities			20 years
Par value of company held auction rate securities	12,000		$ 12,000
Discount rate (in percent)			6.00%		5.00%
Temporary impairment of the auction rates security investments, net of unrealized gain	$ (160)		$ (160)

X

- Definition

Auction rate securities are variable rate investments that have the interest rate on the security set to the market rate on a contractual basis, this element defines the contractual basis period for the security market change in the interest rate.

+ References

No definition available.

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- Definition

This element represents the underlying maturity dates of the securities the auction rate security is based upon.

+ References

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- Definition

Accumulated appreciation or loss, net of tax, in value of the total of available-for-sale securities at the end of an accounting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
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Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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- Definition

The value of securities held, for which the interest rate resets through an auction process, that are categorized neither as trading nor held-to-maturity, that failed to be liquidated through auction.

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Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

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