3. Restricted Marketable Securities (Details) - Available For Sale - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2025	Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 54,199	$ 172,836
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	1,080	1,253
Restricted marketable securities	210,555	199,136
Restricted Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	262,796	256,966
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	14	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	52,255	57,830
Restricted marketable securities	$ 210,555	199,136
Minimum [Member] \| Restricted Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Contractual maturities of Debt securities, Available-for-sale, range start (in years)	6 years
Maximum [Member] \| Restricted Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Contractual Maturities Of Debt securities, Available-for-sale, Range End (In Years)	14 years
U.S. debt [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 10,000	10,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	1,080	1,253
U.S. debt [Member] \| Restricted Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	144,193	144,652
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	31,145	35,497
Restricted marketable securities	113,048	109,155
Foreign government obligations [Member] \| Restricted Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	63,972	62,595
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	13,380	13,571
Restricted marketable securities	50,592	49,024
Supranational debt [Member] \| Restricted Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	30,287	25,351
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	14	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	2,183	2,542
Restricted marketable securities	28,118	22,809
U.S. government obligations [Member] \| Restricted Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	24,344	24,368
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	5,547	6,220
Restricted marketable securities	$ 18,797	$ 18,148

Contractual Maturities Of Debt securities, Available-for-sale, Range End (In Years)

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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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Amortized cost 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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