One-time fee for a royalty-free, fully-paid, perpetual and assignable license to patents.

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Represents potential future payments still contingent upon achievement of milestones under a collaborative arrangement.

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Value of the investment at close of period. For schedules of investments that are categorized, the value would be aggregated by category. For investment in and advances to affiliates, if operations of any controlled companies are different in character from those of the company, group such affiliates within divisions and by type of activities.

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Balance held at close of period in number of shares.

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Price of a single share of a number of saleable stocks of a company.

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LICENSE AND COLLABORATION AGREEMENTS - Biocartis (Details) $ / shares in Units, € in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2020 EUR (€)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2017 EUR (€) shares	Dec. 31, 2017 USD ($) $ / shares shares	Sep. 30, 2017 EUR (€)	Sep. 30, 2017 USD ($)
Sales Milestone Range One
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payments Contingent on Milestones	€ 2.5
Expansion Of Collaboration To Oncology
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Payments Contingent on Milestones	€ 2.0
Biocartis N.V
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Investment owned (in shares) \| shares				270,000	270,000
Market price (in dollars per share) \| $ / shares					$ 12.50
Investment owned, at fair value		$ 1.0	$ 1.7	€ 3.4	$ 4.0
Biocartis N.V \| Licensing Agreements
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
One Time Fee For License To Patents						€ 2.8	$ 3.2