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Fair Value Measurement - Summary of Fair Values and Gross Unrealized Losses of Available for Sale Securities (Detail) - USD ($) $ in Thousands | Jun. 30, 2025 | Dec. 31, 2024
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Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items] |  |
Less than 12 months, Recorded Basis | $ 3,395 | $ 16,364
Less than 12 months, Gross Unrealized Losses | (26) | (82)
12 months or longer, Recorded Basis | 208,920 | 224,185
12 months or longer, Gross Unrealized Losses | (19,846) | (26,566)
Total, Recorded Basis | 212,315 | 240,549
Total, Gross Unrealized Losses | (19,872) | (26,648)
Investments [Member] |  |
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items] |  |
Less than 12 months, Recorded Basis |  | 20
12 months or longer, Recorded Basis | 55,334 | 60,065
12 months or longer, Gross Unrealized Losses | (5,014) | (6,409)
Total, Recorded Basis | 55,334 | 60,085
Total, Gross Unrealized Losses | (5,014) | (6,409)
Restricted Investments [Member] |  |
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items] |  |
Less than 12 months, Recorded Basis | 3,395 | 16,344
Less than 12 months, Gross Unrealized Losses | (26) | (82)
12 months or longer, Recorded Basis | 153,586 | 164,120
12 months or longer, Gross Unrealized Losses | (14,832) | (20,157)
Total, Recorded Basis | 156,981 | 180,464
Total, Gross Unrealized Losses | (14,858) | (20,239)
Corporate Bonds [Member] | Investments [Member] |  |
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items] |  |
Less than 12 months, Recorded Basis |  | 20
12 months or longer, Recorded Basis | 26,028 | 25,377
12 months or longer, Gross Unrealized Losses | (1,660) | (2,365)
Total, Recorded Basis | 26,028 | 25,397
Total, Gross Unrealized Losses | (1,660) | (2,365)
Corporate Bonds [Member] | Restricted Investments [Member] |  |
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items] |  |
Less than 12 months, Recorded Basis | 397 | 11,142
Less than 12 months, Gross Unrealized Losses | (1) | (15)
12 months or longer, Recorded Basis | 72,903 | 71,716
12 months or longer, Gross Unrealized Losses | (5,122) | (7,287)
Total, Recorded Basis | 73,300 | 82,858
Total, Gross Unrealized Losses | (5,123) | (7,302)
U.S. Government Agency Securities [Member] | Investments [Member] |  |
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items] |  |
12 months or longer, Recorded Basis | 5,507 | 12,531
12 months or longer, Gross Unrealized Losses | (455) | (203)
Total, Recorded Basis | 5,507 | 12,531
Total, Gross Unrealized Losses | (455) | (203)
U.S. Government Agency Securities [Member] | Restricted Investments [Member] |  |
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items] |  |
12 months or longer, Recorded Basis | 5,262 | 15,871
12 months or longer, Gross Unrealized Losses | (89) | (914)
Total, Recorded Basis | 5,262 | 15,871
Total, Gross Unrealized Losses | (89) | (914)
U.S. Treasuries [Member] | Investments [Member] |  |
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items] |  |
12 months or longer, Recorded Basis | 13,411 | 11,320
12 months or longer, Gross Unrealized Losses | (849) | (1,140)
Total, Recorded Basis | 13,411 | 11,320
Total, Gross Unrealized Losses | (849) | (1,140)
U.S. Treasuries [Member] | Restricted Investments [Member] |  |
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items] |  |
Less than 12 months, Recorded Basis | 1,219 | 1,399
Less than 12 months, Gross Unrealized Losses | (5) | (29)
12 months or longer, Recorded Basis | 46,592 | 46,656
12 months or longer, Gross Unrealized Losses | (4,535) | (6,319)
Total, Recorded Basis | 47,811 | 48,055
Total, Gross Unrealized Losses | (4,540) | (6,348)
Mortgage-Backed Securities [Member] | Investments [Member] |  |
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items] |  |
12 months or longer, Recorded Basis | 9,329 | 9,536
12 months or longer, Gross Unrealized Losses | (2,335) | (2,592)
Total, Recorded Basis | 9,329 | 9,536
Total, Gross Unrealized Losses | (2,335) | (2,592)
Mortgage-Backed Securities [Member] | Restricted Investments [Member] |  |
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items] |  |
Less than 12 months, Recorded Basis | 1,522 | 3,360
Less than 12 months, Gross Unrealized Losses | (17) | (37)
12 months or longer, Recorded Basis | 28,584 | 29,877
12 months or longer, Gross Unrealized Losses | (4,720) | (5,637)
Total, Recorded Basis | 30,106 | 33,237
Total, Gross Unrealized Losses | (4,737) | (5,674)
Asset-Backed Securities [Member] | Investments [Member] |  |
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items] |  |
12 months or longer, Recorded Basis | 1,304 | 1,301
12 months or longer, Gross Unrealized Losses | (81) | (109)
Total, Recorded Basis | 1,304 | 1,301
Total, Gross Unrealized Losses | (81) | (109)
Asset-Backed Securities [Member] | Restricted Investments [Member] |  |
Debt Securities, Available-for-Sale, Unrealized Loss Position [Line Items] |  |
Less than 12 months, Recorded Basis | 257 | 443
Less than 12 months, Gross Unrealized Losses | (3) | (1)
Total, Recorded Basis | 257 | 443
Total, Gross Unrealized Losses | $ (3) | $ (1)

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