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Cash, Cash Equivalents and Investments - Amortized Cost to Fair Value (Detail) $ in Thousands | Dec. 31, 2016 USD ($)
--- | ---
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | $ 665,464
Gross Unrealized Gains | 913
Gross Unrealized Losses | (848)
Fair Value, Total | 665,529
Euro liquidity fund [Member] |
Schedule of Available-for-sale Securities [Line Items] |
Fair Value, Total | 46,499
Euro liquidity fund [Member] | Short-term investments [Member] |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 46,173
Gross Unrealized Gains | 326
Gross Unrealized Losses | 0
Fair Value, Total | 46,499
Corporate Bonds [Member] |
Schedule of Available-for-sale Securities [Line Items] |
Fair Value, Total | 311,140
Corporate Bonds [Member] | Short-term investments [Member] |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 141,216
Gross Unrealized Gains | 37
Gross Unrealized Losses | (65)
Fair Value, Total | 141,188
Corporate Bonds [Member] | Long-term investments [Member] |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 169,911
Gross Unrealized Gains | 406
Gross Unrealized Losses | (365)
Fair Value, Total | 169,952
Agency Bonds [Member] |
Schedule of Available-for-sale Securities [Line Items] |
Fair Value, Total | 13,242
Agency Bonds [Member] | Short-term investments [Member] |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 2,900
Gross Unrealized Gains | 3
Gross Unrealized Losses | 0
Fair Value, Total | 2,903
Agency Bonds [Member] | Long-term investments [Member] |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 10,310
Gross Unrealized Gains | 29
Gross Unrealized Losses | 0
Fair Value, Total | 10,339
Asset-Backed Securities [Member] |
Schedule of Available-for-sale Securities [Line Items] |
Fair Value, Total | 96,560
Asset-Backed Securities [Member] | Short-term investments [Member] |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 69,623
Gross Unrealized Gains | 18
Gross Unrealized Losses | (27)
Fair Value, Total | 69,614
Asset-Backed Securities [Member] | Long-term investments [Member] |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 26,968
Gross Unrealized Gains | 25
Gross Unrealized Losses | (47)
Fair Value, Total | 26,946
Municipal Bonds [Member] |
Schedule of Available-for-sale Securities [Line Items] |
Fair Value, Total | 7,750
Municipal Bonds [Member] | Short-term investments [Member] |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 6,517
Gross Unrealized Gains | 2
Gross Unrealized Losses | (2)
Fair Value, Total | 6,517
Municipal Bonds [Member] | Long-term investments [Member] |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 1,236
Gross Unrealized Gains | 0
Gross Unrealized Losses | (3)
Fair Value, Total | 1,233
Treasury Bills [Member] |
Schedule of Available-for-sale Securities [Line Items] |
Fair Value, Total | 159,455
Treasury Bills [Member] | Short-term investments [Member] |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 67,201
Gross Unrealized Gains | 21
Gross Unrealized Losses | (47)
Fair Value, Total | 67,175
Treasury Bills [Member] | Long-term investments [Member] |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 92,392
Gross Unrealized Gains | 40
Gross Unrealized Losses | (152)
Fair Value, Total | 92,280
Sovereign Bonds [Member] |
Schedule of Available-for-sale Securities [Line Items] |
Fair Value, Total | 30,883
Sovereign Bonds [Member] | Short-term investments [Member] |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 7,313
Gross Unrealized Gains | 0
Gross Unrealized Losses | (15)
Fair Value, Total | 7,298
Sovereign Bonds [Member] | Long-term investments [Member] |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 23,704
Gross Unrealized Gains | 6
Gross Unrealized Losses | (125)
Fair Value, Total | $ 23,585

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