| Fair Value, by Balance Sheet Grouping [Table Text Block] |
| | | September 30, 2026 | |
| | | (in thousands) | |
| | | Level 1 | | | Level 2 | | | Level 3 | | | Total | |
| Assets | | | | | | | | | | | | | | | | |
| Cash Equivalents: | | | | | | | | | | | | | | | | |
| Certificates of deposit (1) | | $ | — | | | $ | 28,971 | | | $ | — | | | $ | 28,971 | |
| Money market funds | | | — | | | | 18,891 | | | | — | | | | 18,891 | |
| U.S. treasury bills | | | — | | | | 294,554 | | | | — | | | | 294,554 | |
| Prepaid expenses and other current assets: | | | | | | | | | | | | | | | | |
| Certificates of deposit (1) | | | — | | | | 7,588 | | | | — | | | | 7,588 | |
| Other assets: | | | | | | | | | | | | | | | | |
| Certificates of deposit (1) | | | — | | | | 225 | | | | — | | | | 225 | |
| Total | | $ | — | | | $ | 350,229 | | | $ | — | | | $ | 350,229 | |
| Liabilities: | | | | | | | | | | | | | | | | |
| Accrued expenses and other current liabilities: | | | | | | | | | | | | | | | | |
| Mandatorily redeemable noncontrolling interest (2) | | $ | — | | | $ | — | | | $ | 2,262 | | | $ | 2,262 | |
| Other liabilities: | | | | | | | | | | | | | | | | |
| Mandatorily redeemable noncontrolling interest (2) | | | — | | | | — | | | | 2,106 | | | | 2,106 | |
| Total | | $ | — | | | $ | — | | | $ | 4,368 | | | $ | 4,368 | |
| | | December 31, 2025 | |
| | | (in thousands) | |
| | | Level 1 | | | Level 2 | | | Level 3 | | | Total | |
| Assets | | | | | | | | | | | | | | | | |
| Cash Equivalents: | | | | | | | | | | | | | | | | |
| Certificates of deposit (1) | | $ | — | | | $ | 1,734 | | | $ | — | | | $ | 1,734 | |
| Money market funds | | | — | | | | 4,215 | | | | — | | | | 4,215 | |
| U.S. treasury bills | | | — | | | | 189,012 | | | | — | | | | 189,012 | |
| Prepaid expenses and other current assets: | | | | | | | | | | | | | | | | |
| Certificates of deposit (1) | | | — | | | | 213 | | | | — | | | | 213 | |
| Other assets: | | | | | | | | | | | | | | | | |
| Certificates of deposit (1) | | | — | | | | 206 | | | | — | | | | 206 | |
| Total | | $ | — | | | $ | 195,380 | | | $ | — | | | $ | 195,380 | |
| Liabilities: | | | | | | | | | | | | | | | | |
| Accrued expenses and other current liabilities: | | | | | | | | | | | | | | | | |
| Mandatorily redeemable noncontrolling interest (2) | | $ | — | | | $ | — | | | $ | 1,839 | | | $ | 1,839 | |
| Other liabilities: | | | | | | | | | | | | | | | | |
| Mandatorily redeemable noncontrolling interest (2) | | | — | | | | — | | | | 3,704 | | | | 3,704 | |
| Total | | $ | — | | | $ | — | | | $ | 5,543 | | | $ | 5,543 | |
|
| Debt Securities, Available-for-Sale [Table Text Block] |
| | | September 30, 2026 | |
| | | (in thousands) | |
| | | Amortized Cost | | | Fair Value | | | Gross Unrealized Losses | |
| U.S. treasury bills | | $ | 294,582 | | | $ | 294,554 | | | $ | (28 | ) |
| Total | | $ | 294,582 | | | $ | 294,554 | | | $ | (28 | ) |
| | | December 31, 2025 | |
| | | (in thousands) | |
| | | Amortized Cost | | | Fair Value | | | Gross Unrealized Gains | |
| U.S. treasury bills | | $ | 189,007 | | | $ | 189,012 | | | $ | 5 | |
| Total | | $ | 189,007 | | | $ | 189,012 | | | $ | 5 | |
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