Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Components of Long-Term Debt and Methods Used in Estimating Fair Values

The following table summarizes components of the Company’s long-term debt and methods used in estimating their fair values:

	Maturity
	Date	Valuation Methodology
4.75% Convertible Senior Notes	2042	Quoted price
4.25% Convertible Senior Notes	2037	Quoted price
3.90% Promissory Note	*	Discounted cash flow method/Level 3 inputs
3.75% Callable Promissory Note	*	Discounted cash flow method/Level 3 inputs
4.55% Promissory Note	2036	Discounted cash flow method/Level 3 inputs
5.50% Promissory Note	2033	Discounted cash flow method/Level 3 inputs

* Debt derecognized in March 2023. See Note 13 -- “Long-Term Debt” for additional information.

Assets Measured at Estimated Fair Value on a Recurring Basis

The following tables present information about the Company’s financial assets measured at estimated fair value on a recurring basis. The tables indicate the fair value hierarchy of the valuation techniques utilized by the Company to determine such fair value as of December 31, 2023 and 2022:

	Fair Value Measurements Using
	(Level 1)		(Level 2)		(Level 3)		Total
As of December 31, 2023
Financial Assets:
Cash and cash equivalents	$	536,478	$	—	$	—	$	536,478
Restricted cash	$	3,287	$	—	$	—	$	3,287
Fixed-maturity securities:
U.S. Treasury and U.S. government agencies	$	348,145	$	7,909	$	—	$	356,054
Corporate bonds		20,267		6,437		—		26,704
Exchange-traded debt		480		—		—		480
Total available-for-sale securities	$	368,892	$	14,346	$	—	$	383,238
Equity securities	$	45,537	$	—	$	—	$	45,537

	Fair Value Measurements Using
	(Level 1)		(Level 2)		(Level 3)		Total
As of December 31, 2022
Financial Assets:
Cash and cash equivalents	$	234,863	$	—	$	—	$	234,863
Restricted cash	$	2,900	$	—	$	—	$	2,900
Fixed-maturity securities:
U.S. Treasury and U.S. government agencies	$	446,233	$	8,369	$	—	$	454,602
Corporate bonds		27,193		—		—		27,193
States, municipalities, and political subdivisions		—		1,383		—		1,383
Exchange-traded debt		633		—		—		633
Redeemable preferred stock		90		—		—		90
Total available-for-sale securities	$	474,149	$	9,752	$	—	$	483,901
Equity securities	$	34,583	$	—	$	—	$	34,583

Schedule of Fair Value Information for Financial Liabilities Carried on Balance Sheet

The following tables present fair value information for liabilities that are carried on the consolidated balance sheets at amounts other than fair value as of December 31, 2023 and 2022:

	Carrying		Fair Value Measurements Using						Estimated
	Value		(Level 1)		(Level 2)		(Level 3)		Fair Value
As of December 31, 2023
Financial Liabilities:
Long-term debt:
4.75% Convertible Senior Notes	$	168,230	$	—	$	215,114	$	—	$	215,114
4.25% Convertible Senior Notes		23,916		—		34,545		—		34,545
5.50% Promissory Note		11,707		—		—		11,512		11,512
4.55% Promissory Note		4,640		—		—		4,349		4,349
Total long-term debt	$	208,493	$	—	$	249,659	$	15,861	$	265,520

	Carrying		Fair Value Measurements Using						Estimated
	Value		(Level 1)		(Level 2)		(Level 3)		Fair Value
As of December 31, 2022
Financial Liabilities:
Long-term debt:
4.75% Convertible Senior Notes	$	167,126	$	—	$	133,167	$	—	$	133,167
4.25% Convertible Senior Notes		23,916		—		19,473		—		19,473
3.90% Promissory Note		8,943		—		—		8,152		8,152
3.75% Callable Promissory Note		6,789		—		—		6,171		6,171
4.55% Promissory Note		4,900		—		—		4,642		4,642
Total long-term debt	$	211,674	$	—	$	152,640	$	18,965	$	171,605