Note 6. Restricted Marketable Securities (Details) - Available For Sale - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	$ 52,562	$ 172,836
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gains, before Tax	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Losses, before Tax	713	1,253
Restricted marketable securities	217,172	199,136
Restricted debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	264,278	256,966
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gains, before Tax	59	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Losses, before Tax	47,165	57,830
Restricted marketable securities	$ 217,172	199,136
Minimum [Member] | Restricted debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Contractual maturities of available-for-sale marketable securities, range start (in years)	5 years
Maximum [Member] | Restricted debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Contractual maturities of available-for-sale marketable securities, 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 Gains, before Tax	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Losses, before Tax	713	1,253
U.S. debt [Member] | Restricted debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	142,790	144,652
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gains, before Tax	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Losses, before Tax	27,440	35,497
Restricted marketable securities	115,350	109,155
Foreign government obligations [Member] | Restricted debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	67,091	62,595
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gains, before Tax	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Losses, before Tax	12,935	13,571
Restricted marketable securities	54,156	49,024
Supranational debt [Member] | Restricted debt securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Amortized Cost	30,123	25,351
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gains, before Tax	59	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Losses, before Tax	1,906	2,542
Restricted marketable securities	28,276	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	24,274	24,368
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gains, before Tax	0	0
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Losses, before Tax	4,884	6,220
Restricted marketable securities	$ 19,390	$ 18,148