v3.19.3

INVESTMENTS - Short-Term and Long-Term Investments (Details) - USD ($) $ in Thousands | Sep. 30, 2019 | Dec. 31, 2018
--- | --- | ---
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | $ 1,122,269 |
Fair Value | 1,122,164 |
Short-term Investments |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 557,380 | $ 541,684
Gross Unrealized Gains | 773 | 329
Gross Unrealized Losses | (497) | (1,022)
Fair Value | 557,656 | 540,991
Long-term Investments |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 564,889 | 464,545
Gross Unrealized Gains | 790 | 1,361
Gross Unrealized Losses | (1,171) | (1,226)
Fair Value | 564,508 | 464,680
U.S. agency securities | Short-term Investments |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 132,217 | 80,160
Gross Unrealized Gains | 257 | 32
Gross Unrealized Losses | (126) | (70)
Fair Value | 132,348 | 80,122
U.S. agency securities | Long-term Investments |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 87,848 | 114,444
Gross Unrealized Gains | 219 | 194
Gross Unrealized Losses | (164) | (78)
Fair Value | 87,903 | 114,560
Corporate bonds | Short-term Investments |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 55,399 | 109,807
Gross Unrealized Gains | 194 | 80
Gross Unrealized Losses | (92) | (368)
Fair Value | 55,501 | 109,519
Corporate bonds | Long-term Investments |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 185,675 | 159,783
Gross Unrealized Gains | 286 | 419
Gross Unrealized Losses | (398) | (950)
Fair Value | 185,563 | 159,252
Commercial paper | Short-term Investments |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 2,245 |
Gross Unrealized Gains | 0 |
Gross Unrealized Losses | 0 |
Fair Value | 2,245 |
Municipal securities | Short-term Investments |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 2,713 | 27,839
Gross Unrealized Gains | 5 | 52
Gross Unrealized Losses | (49) | (59)
Fair Value | 2,669 | 27,832
Municipal securities | Long-term Investments |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 12,668 | 28,453
Gross Unrealized Gains | 12 | 167
Gross Unrealized Losses | (98) | (26)
Fair Value | 12,582 | 28,594
U.S. government securities | Short-term Investments |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 351,592 | 292,615
Gross Unrealized Gains | 317 | 161
Gross Unrealized Losses | (192) | (509)
Fair Value | 351,717 | 292,267
U.S. government securities | Long-term Investments |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 250,434 | 153,743
Gross Unrealized Gains | 267 | 553
Gross Unrealized Losses | (436) | (172)
Fair Value | 250,265 | 154,124
Foreign securities | Short-term Investments |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 13,214 | 31,263
Gross Unrealized Gains | 0 | 4
Gross Unrealized Losses | (38) | (16)
Fair Value | 13,176 | 31,251
Foreign securities | Long-term Investments |  |
Debt Securities, Available-for-sale [Line Items] |  |
Amortized Cost | 28,264 | 8,122
Gross Unrealized Gains | 6 | 28
Gross Unrealized Losses | (75) | 0
Fair Value | $ 28,195 | $ 8,150

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