Fair Value Measurements. Cash Equivalents and Marketable Securities - Narrative (Details) - USD ($)	1 Months Ended		12 Months Ended
	Jul. 31, 2022	May 31, 2018	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Realized gain (loss) on marketable debt securities			$ 0	$ 0	$ 0
Recognition of credit losses			0	0	0
SoftBank
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Threshold percentage of fair value that is no less than internal rate of return (as a percent)		20.00%
Fair value, measurements, recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term marketable debt securities			98,002,000	18,291,000
Initial fair value of contingent consideration at acquisition date			6,540,000	6,430,000
Level 1 | Fair value, measurements, recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term marketable debt securities			98,002,000	18,291,000
Initial fair value of contingent consideration at acquisition date			0	0
Level 3 | Fair value, measurements, recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term marketable debt securities			0	0
Initial fair value of contingent consideration at acquisition date			6,540,000	6,430,000
Contingent consideration liability, noncurrent			5,000,000	4,900,000
Lunit Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Lock up period (in years)	2 years
Unrealized (loss) gain on marketable equity securities			79,700,000	(7,800,000)
Unrealized gain (loss) on investments					$ 0
Lunit Inc. | Level 1 | Fair value, measurements, recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term marketable debt securities			$ 98,000,000	$ 18,300,000
Guardant Health AMEA, Inc | SoftBank
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Redeemable noncontrolling interest, redemption value		$ 41,000,000