FAIR VALUE MEASUREMENTS (Details) - Recurring basis - USD ($)
$ in Thousands |
Sep. 30, 2016 |
Dec. 31, 2015 |
| Fair value |
|
|
| Assets, Total |
$ 480,595
|
$ 673,146
|
| Level 1 |
|
|
| Fair value |
|
|
| Assets, Total |
141,943
|
216,122
|
| Level 2 |
|
|
| Fair value |
|
|
| Assets, Total |
278,707
|
399,903
|
| Level 3 |
|
|
| Fair value |
|
|
| Assets, Total |
59,945
|
57,121
|
| Cash equivalents |
|
|
| Fair value |
|
|
| Estimated Fair Value |
1,667
|
1,666
|
| Cash equivalents | Level 1 |
|
|
| Fair value |
|
|
| Estimated Fair Value |
1,667
|
1,666
|
| U.S. government and agency debt securities |
|
|
| Fair value |
|
|
| Estimated Fair Value |
250,943
|
352,188
|
| U.S. government and agency debt securities | Level 1 |
|
|
| Fair value |
|
|
| Estimated Fair Value |
140,276
|
214,456
|
| U.S. government and agency debt securities | Level 2 |
|
|
| Fair value |
|
|
| Estimated Fair Value |
110,667
|
137,732
|
| Corporate debt securities |
|
|
| Fair value |
|
|
| Estimated Fair Value |
151,520
|
213,209
|
| Corporate debt securities | Level 2 |
|
|
| Fair value |
|
|
| Estimated Fair Value |
151,520
|
213,209
|
| International government agency debt securities |
|
|
| Fair value |
|
|
| Estimated Fair Value |
16,520
|
48,962
|
| International government agency debt securities | Level 2 |
|
|
| Fair value |
|
|
| Estimated Fair Value |
16,520
|
48,962
|
| Contingent Consideration |
|
|
| Fair value |
|
|
| Assets, Total |
58,400
|
55,300
|
| Contingent Consideration | Level 3 |
|
|
| Fair value |
|
|
| Assets, Total |
58,400
|
55,300
|
| Equity securities |
|
|
| Fair value |
|
|
| Estimated Fair Value |
1,545
|
1,821
|
| Equity securities | Level 3 |
|
|
| Fair value |
|
|
| Estimated Fair Value |
$ 1,545
|
$ 1,821
|