Schedule of Carrying Amounts and Fair Values of Financial Instruments (Detail) - USD ($) $ in Thousands |
Sep. 30, 2018 |
Dec. 31, 2017 |
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Fair Value, Balance Sheet Grouping, Financial Statement Captions | |||||
Marketable securities | $ 485,707 | $ 1,473,905 | |||
Carrying Value | |||||
Fair Value, Balance Sheet Grouping, Financial Statement Captions | |||||
Cash and cash equivalents | 814,019 | 429,843 | |||
Marketable securities | 510,392 | 1,473,905 | |||
Derivative assets | 3 | 389 | |||
Contingent consideration | 60,942 | 45,102 | |||
Derivative liabilities | 455 | 446 | |||
Convertible debt | [1] | 376,417 | 365,987 | ||
Fair Value | |||||
Fair Value, Balance Sheet Grouping, Financial Statement Captions | |||||
Cash and cash equivalents | 814,019 | 429,843 | |||
Marketable securities | 510,392 | 1,473,905 | |||
Derivative assets | 3 | 389 | |||
Contingent consideration | 60,942 | 45,102 | |||
Derivative liabilities | 455 | 446 | |||
Convertible debt | [1] | $ 599,438 | $ 659,525 | ||
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