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+ References

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+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 25

-Paragraph 1

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Cash

-URI http://asc.fasb.org/extlink&oid=6506951

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-Publisher FASB

-Name Accounting Standards Codification

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FAIR VALUE MEASUREMENTS (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
FAIR VALUE MEASUREMENTS
Short-term investments	$ 602,559	$ 0
Corporate notes and bonds
FAIR VALUE MEASUREMENTS
Short-term investments	429,270
U.S. agency obligations
FAIR VALUE MEASUREMENTS
Short-term investments	68,289
U.S. treasury securities
FAIR VALUE MEASUREMENTS
Short-term investments	55,436
Commercial paper
FAIR VALUE MEASUREMENTS
Short-term investments	39,242
Certificate of deposit
FAIR VALUE MEASUREMENTS
Short-term investments	10,322
Recurring \| Total
FAIR VALUE MEASUREMENTS
Total	714,269
Recurring \| Money market funds \| Total
FAIR VALUE MEASUREMENTS
Cash Equivalents	3,133
Recurring \| Corporate notes and bonds \| Total
FAIR VALUE MEASUREMENTS
Cash Equivalents	34,482
Recurring \| U.S. agency obligations \| Total
FAIR VALUE MEASUREMENTS
Cash Equivalents	30,207
Recurring \| Commercial paper \| Total
FAIR VALUE MEASUREMENTS
Cash Equivalents	43,888
Recurring \| Level 1
FAIR VALUE MEASUREMENTS
Total	3,133
Recurring \| Level 1 \| Money market funds
FAIR VALUE MEASUREMENTS
Cash Equivalents	3,133
Recurring \| Level 2
FAIR VALUE MEASUREMENTS
Total	711,136
Recurring \| Level 2 \| Corporate notes and bonds
FAIR VALUE MEASUREMENTS
Cash Equivalents	34,482
Recurring \| Level 2 \| U.S. agency obligations
FAIR VALUE MEASUREMENTS
Cash Equivalents	30,207
Recurring \| Level 2 \| Commercial paper
FAIR VALUE MEASUREMENTS
Cash Equivalents	43,888
Recurring \| Corporate notes and bonds \| Total
FAIR VALUE MEASUREMENTS
Short-term investments	429,270
Recurring \| Corporate notes and bonds \| Level 2
FAIR VALUE MEASUREMENTS
Short-term investments	429,270
Recurring \| U.S. agency obligations \| Total
FAIR VALUE MEASUREMENTS
Short-term investments	68,289
Recurring \| U.S. agency obligations \| Level 2
FAIR VALUE MEASUREMENTS
Short-term investments	68,289
Recurring \| U.S. treasury securities \| Total
FAIR VALUE MEASUREMENTS
Short-term investments	55,436
Recurring \| U.S. treasury securities \| Level 2
FAIR VALUE MEASUREMENTS
Short-term investments	55,436
Recurring \| Commercial paper \| Total
FAIR VALUE MEASUREMENTS
Short-term investments	39,242
Recurring \| Commercial paper \| Level 2
FAIR VALUE MEASUREMENTS
Short-term investments	39,242
Recurring \| Certificate of deposit \| Total
FAIR VALUE MEASUREMENTS
Short-term investments	10,322
Recurring \| Certificate of deposit \| Level 2
FAIR VALUE MEASUREMENTS
Short-term investments	$ 10,322