Variable Interest Entities - Schedule of Consolidated VIE Assets and Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023	Dec. 31, 2022
Variable Interest Entity [Line Items]
Cash and cash equivalents	$ 82,145	$ 100,073
Accounts receivable, net	383,945	361,451
Other current assets	185,972	134,476
Total current assets	652,062	596,000
Property and equipment, net	2,679,807	2,266,610
Goodwill	2,264,851	2,225,962	$ 2,222,805
Intangible assets, net	73,139	73,278
Operating lease right-of-use assets	122,771	117,780
Total assets	5,870,457	5,358,841
Accounts payable	201,379	156,132
Accrued salaries and benefits	141,470	141,901
Current portion of operating lease liabilities	27,175	26,268
Other accrued liabilities	167,782	532,261
Total current liabilities	609,500	885,781
Operating lease liabilities	105,437	100,808
Other liabilities	150,544	140,113
Total liabilities	2,724,418	2,471,181
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Cash and cash equivalents	82,473	55,149
Accounts receivable, net	41,536	34,910
Other current assets	7,545	2,193
Total current assets	131,554	92,252
Property and equipment, net	614,281	438,965
Goodwill	42,384	42,384
Intangible assets, net	18,342	18,295
Operating lease right-of-use assets	9,895	5,948
Total assets	816,456	597,844
Accounts payable	9,700	8,235
Accrued salaries and benefits	8,615	9,909
Current portion of operating lease liabilities	593	273
Other accrued liabilities	4,151	2,385
Total current liabilities	23,059	20,802
Operating lease liabilities	9,900	6,160
Total liabilities	$ 32,959	$ 26,962