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Fair Value Measurement - Summary of Investments Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands | Jun. 30, 2025 | Dec. 31, 2024
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Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Cost | $ 272,153 | $ 325,163
Gross Unrealized Gains | 145 | 48
Gross Unrealized Losses | (19,872) | (26,648)
Recorded Basis | 252,426 | 298,563
Cash and Cash Equivalents [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Cost | 8,314 | 26,661
Recorded Basis | 8,314 | 26,661
Investments [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Cost | 69,096 | 72,886
Gross Unrealized Gains | 15 | 15
Gross Unrealized Losses | (5,014) | (6,409)
Recorded Basis | 64,097 | 66,492
Restricted Cash and Investments [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Cost | 194,743 | 225,616
Gross Unrealized Gains | 130 | 33
Gross Unrealized Losses | (14,858) | (20,239)
Recorded Basis | 180,015 | 205,410
Money Market Funds [Member] | Cash and Cash Equivalents [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Cost | 8,314 | 26,661
Recorded Basis | 8,314 | 26,661
Money Market Funds [Member] | Restricted Cash and Investments [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Cost | 101 | 216
Recorded Basis | 101 | 216
Corporate Bonds [Member] | Investments [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Cost | 27,901 | 27,954
Gross Unrealized Gains | 5 | 3
Gross Unrealized Losses | (1,660) | (2,365)
Recorded Basis | 26,246 | 25,592
Corporate Bonds [Member] | Restricted Cash and Investments [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Cost | 81,572 | 100,030
Gross Unrealized Gains | 51 | 16
Gross Unrealized Losses | (5,123) | (7,302)
Recorded Basis | 76,500 | 92,744
U.S. Treasuries [Member] | Investments [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Cost | 14,260 | 12,460
Gross Unrealized Losses | (849) | (1,140)
Recorded Basis | 13,411 | 11,320
U.S. Treasuries [Member] | Restricted Cash and Investments [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Cost | 53,054 | 54,900
Gross Unrealized Gains | 11 |
Gross Unrealized Losses | (4,540) | (6,348)
Recorded Basis | 48,525 | 48,552
Mortgage-Backed Securities [Member] | Investments [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Cost | 11,663 | 12,128
Gross Unrealized Losses | (2,335) | (2,592)
Recorded Basis | 9,328 | 9,536
Mortgage-Backed Securities [Member] | Restricted Cash and Investments [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Cost | 39,274 | 40,858
Gross Unrealized Gains | 53 | 10
Gross Unrealized Losses | (4,737) | (5,674)
Recorded Basis | 34,590 | 35,194
U.S. Government Agency Securities [Member] | Investments [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Cost | 7,687 | 12,734
Gross Unrealized Losses | (89) | (203)
Recorded Basis | 7,598 | 12,531
U.S. Government Agency Securities [Member] | Restricted Cash and Investments [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Cost | 6,686 | 16,785
Gross Unrealized Losses | (455) | (914)
Recorded Basis | 6,231 | 15,871
Asset-Backed Securities [Member] | Investments [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Cost | 7,585 | 7,610
Gross Unrealized Gains | 10 | 12
Gross Unrealized Losses | (81) | (109)
Recorded Basis | 7,514 | 7,513
Asset-Backed Securities [Member] | Restricted Cash and Investments [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Cost | 1,527 | 1,666
Gross Unrealized Gains | 9 | 6
Gross Unrealized Losses | (3) | (1)
Recorded Basis | 1,533 | 1,671
Emerging Markets [Member] | Restricted Cash and Investments [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Cost | 199 | 200
Gross Unrealized Gains | 6 | 1
Recorded Basis | 205 | 201
Mutual Funds [Member] | Restricted Cash and Investments [Member] |  |
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] |  |
Cost | 12,330 | 10,961
Recorded Basis | $ 12,330 | $ 10,961

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