FAIR VALUE MEASUREMENTS (Tables)

12 Months Ended

Dec. 31, 2015

Fair Value Disclosures [Abstract]

Financial instruments carried at fair value

Financial assets and liabilities are carried at fair value as of December 31, 2015 and are classified in the categories described in the tables below (in thousands):

	Level 1		Level 2		Total
ASSETS:
Cash equivalents:
U.S. Treasury money market funds	$	99,117	$	—	$	99,117
Foreign government securities	—		10,659		10,659
U.S. government securities	—		90,441		90,441
Corporate debt securities	—		1,855		1,855
Commercial paper	—		335,663		335,663
Short-term investments:
Foreign government securities	—		395,797		395,797
U.S. government securities	—		456,494		456,494
Corporate debt securities	—		305,260		305,260
Commercial paper	—		11,688		11,688
U.S. government agency securities	—		2,007		2,007
Foreign exchange derivatives	—		363		363
Long-term investments:
Foreign government securities	—		719,631		719,631
U.S. government securities	—		578,450		578,450
Corporate debt securities	—		4,276,614		4,276,614
U.S. municipal securities	—		1,083		1,083
Ctrip convertible debt securities	—		1,378,550		1,378,550
Ctrip equity securities	977,035		—		977,035
Total assets at fair value	$	1,076,152	$	8,564,555	$	9,640,707

	Level 1		Level 2		Total
LIABILITIES:
Foreign exchange derivatives	$	—	$	644	$	644

Financial assets and liabilities are carried at fair value as of December 31, 2014 and are classified in the categories described in the tables below (in thousands):

	Level 1		Level 2		Total
ASSETS:
Cash equivalents:
U.S. Treasury money market funds	$	155,608	$	—	$	155,608
Foreign government securities	—		974,855		974,855
U.S. government securities	—		676,503		676,503
Corporate debt securities	—		45,340		45,340
Commercial paper	—		382,544		382,544
U.S. government agency securities	—		10,000		10,000
Short-term investments:
Foreign government securities	—		52,490		52,490
U.S. government securities	—		364,266		364,266
Corporate debt securities	—		581,523		581,523
Commercial paper	—		39,092		39,092
U.S. government agency securities	—		104,811		104,811
Foreign exchange derivatives	—		336		336
Long-term investments:
Foreign government securities	—		12,671		12,671
U.S. government securities	—		556,448		556,448
Corporate debt securities	—		2,329,033		2,329,033
U.S. government agency securities	—		95,094		95,094
U.S. municipal securities	—		1,102		1,102
Ctrip convertible debt securities	—		425,961		425,961
Ctrip equity securities	335,344		—		335,344
Total assets at fair value	$	490,952	$	6,652,069	$	7,143,021

	Level 1		Level 2		Total
LIABILITIES:
Foreign exchange derivatives	$	—	$	129	$	129