Marketable Securities - Narrative (Details)	Dec. 31, 2019 USD ($) security	Dec. 31, 2018 USD ($) security
Investments, Debt and Equity Securities [Abstract]
Number of debt securities in unrealized loss position, more than 12 months \| security	0	0
Number of debt securities in unrealized loss position, less than 12 months \| security	8	1
Aggregate unrealized loss on debt securities	$ 6,000.0	$ 755,000
Fair value of debt securities	42,500,000	177,100,000
Available-for-sale securities, gross unrealized gains	9,000.0	0.0
Fair value gain of debt securities	48,500,000	$ 0.0
Aggregate fair value of marketable securities maturing within one year	$ 91,000,000.0

Debt Securities, Available-for-sale, Continuous Unrealized Gain Position, Less than 12 Months

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- Definition

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), maturing in next fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without an allowance for credit loss. Includes beneficial interest in securitized financial asset.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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