Investments and Fair Value Measurements - Narrative (Details) - USD ($)	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Estimated fair values	$ 266,497,000		$ 559,942,000
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Credit losses recognized	0	$ 0
Allowance for credit losses	0		0
Realized gains or losses	800,000	$ 0
Other long-term investments
Fair Value Disclosures [Abstract]
Estimated fair values			$ 155,690,000
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Proceeds from sale of investments	$ 161,300,000

Amount of 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 of allowance for credit loss 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 of realized gain (loss) 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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