FAIR VALUE MEASUREMENTS (Details) (Recurring Basis, USD $)	Dec. 31, 2014	Dec. 31, 2013
ASSETS:
Total assets at fair value	$ 7,143,021,000	$ 6,163,064,000
Level 1
ASSETS:
Total assets at fair value	490,952,000	433,850,000
Level 2
ASSETS:
Total assets at fair value	6,652,069,000	5,729,214,000
Cash equivalents | Money market funds
ASSETS:
Total assets at fair value	155,608,000	433,850,000
Cash equivalents | Foreign government securities
ASSETS:
Total assets at fair value	974,855,000	238,202,000
Cash equivalents | U.S. government securities
ASSETS:
Total assets at fair value	676,503,000	28,000,000
Cash equivalents | U.S. commercial paper
ASSETS:
Total assets at fair value	427,884,000
Cash equivalents | U.S. government agency securities
ASSETS:
Total assets at fair value	10,000,000
Cash equivalents | Level 1 | Money market funds
ASSETS:
Total assets at fair value	155,608,000	433,850,000
Cash equivalents | Level 1 | Foreign government securities
ASSETS:
Total assets at fair value	0	0
Cash equivalents | Level 1 | U.S. government securities
ASSETS:
Total assets at fair value	0	0
Cash equivalents | Level 1 | U.S. commercial paper
ASSETS:
Total assets at fair value	0
Cash equivalents | Level 1 | U.S. government agency securities
ASSETS:
Total assets at fair value	0
Cash equivalents | Level 2 | Money market funds
ASSETS:
Total assets at fair value	0	0
Cash equivalents | Level 2 | Foreign government securities
ASSETS:
Total assets at fair value	974,855,000	238,202,000
Cash equivalents | Level 2 | U.S. government securities
ASSETS:
Total assets at fair value	676,503,000	28,000,000
Cash equivalents | Level 2 | U.S. commercial paper
ASSETS:
Total assets at fair value	427,884,000
Cash equivalents | Level 2 | U.S. government agency securities
ASSETS:
Total assets at fair value	10,000,000
Short-term Investments | Foreign government securities
ASSETS:
Total assets at fair value	52,490,000	4,019,407,000
Short-term Investments | U.S. government securities
ASSETS:
Total assets at fair value	364,266,000	1,443,313,000
Short-term Investments | U.S. commercial paper
ASSETS:
Total assets at fair value	620,615,000
Short-term Investments | U.S. government agency securities
ASSETS:
Total assets at fair value	104,811,000
Short-term Investments | Level 1 | Foreign government securities
ASSETS:
Total assets at fair value	0	0
Short-term Investments | Level 1 | U.S. government securities
ASSETS:
Total assets at fair value	0	0
Short-term Investments | Level 1 | U.S. commercial paper
ASSETS:
Total assets at fair value	0
Short-term Investments | Level 1 | U.S. government agency securities
ASSETS:
Total assets at fair value	0
Short-term Investments | Level 2 | Foreign government securities
ASSETS:
Total assets at fair value	52,490,000	4,019,407,000
Short-term Investments | Level 2 | U.S. government securities
ASSETS:
Total assets at fair value	364,266,000	1,443,313,000
Short-term Investments | Level 2 | U.S. commercial paper
ASSETS:
Total assets at fair value	620,615,000
Short-term Investments | Level 2 | U.S. government agency securities
ASSETS:
Total assets at fair value	104,811,000
Long-term Investments | Foreign government securities
ASSETS:
Total assets at fair value	12,671,000
Long-term Investments | U.S. government securities
ASSETS:
Total assets at fair value	556,448,000
Long-term Investments | U.S. government agency securities
ASSETS:
Total assets at fair value	95,094,000
Long-term Investments | U.S. municipal securities
ASSETS:
Total assets at fair value	1,102,000
Long-term Investments | U.S. corporate debt securities
ASSETS:
Total assets at fair value	2,329,033,000
Long-term Investments | Ctrip corporate debt securities
ASSETS:
Total assets at fair value	425,961,000
Long-term Investments | Ctrip equity securities
ASSETS:
Total assets at fair value	335,344,000
Long-term Investments | Level 1 | Foreign government securities
ASSETS:
Total assets at fair value	0
Long-term Investments | Level 1 | U.S. government securities
ASSETS:
Total assets at fair value	0
Long-term Investments | Level 1 | U.S. government agency securities
ASSETS:
Total assets at fair value	0
Long-term Investments | Level 1 | U.S. municipal securities
ASSETS:
Total assets at fair value	0
Long-term Investments | Level 1 | U.S. corporate debt securities
ASSETS:
Total assets at fair value	0
Long-term Investments | Level 1 | Ctrip corporate debt securities
ASSETS:
Total assets at fair value	0
Long-term Investments | Level 1 | Ctrip equity securities
ASSETS:
Total assets at fair value	335,344,000
Long-term Investments | Level 2 | Foreign government securities
ASSETS:
Total assets at fair value	12,671,000
Long-term Investments | Level 2 | U.S. government securities
ASSETS:
Total assets at fair value	556,448,000
Long-term Investments | Level 2 | U.S. government agency securities
ASSETS:
Total assets at fair value	95,094,000
Long-term Investments | Level 2 | U.S. municipal securities
ASSETS:
Total assets at fair value	1,102,000
Long-term Investments | Level 2 | U.S. corporate debt securities
ASSETS:
Total assets at fair value	2,329,033,000
Long-term Investments | Level 2 | Ctrip corporate debt securities
ASSETS:
Total assets at fair value	425,961,000
Long-term Investments | Level 2 | Ctrip equity securities
ASSETS:
Total assets at fair value	0
Foreign exchange derivatives
LIABILITIES:
Total liabilities at fair value	129,000	122,091,000
Foreign exchange derivatives | Level 1
LIABILITIES:
Total liabilities at fair value	0	0
Foreign exchange derivatives | Level 2
LIABILITIES:
Total liabilities at fair value	129,000	122,091,000
Foreign exchange derivatives | Short-term Investments
ASSETS:
Total assets at fair value	336,000	292,000
Foreign exchange derivatives | Short-term Investments | Level 1
ASSETS:
Total assets at fair value	0	0
Foreign exchange derivatives | Short-term Investments | Level 2
ASSETS:
Total assets at fair value	$ 336,000	$ 292,000