v3.26.3
Segment and Geographic Information - Schedule of Geographic Distributions of Revenues, Equity in Earnings or Losses of Affiliates, Adjusted Segment EBITDA, Depreciation and Amortization (Detail) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Dec. 31, 2025
Segment Reporting Information [Line Items]          
Revenues $ 19,849 $ 19,161 $ 59,188 $ 56,087  
Salaries and benefits 8,581 8,364 25,154 24,499  
Supplies 2,822 2,782 8,561 8,390  
Other operating expenses 4,548 4,161 13,771 11,799  
Equity in earnings of affiliates (20) (16) (45) (53)  
Depreciation and amortization 954 889 2,828 2,612  
Interest expense 607 561 1,790 1,676  
Losses (gains) on sales of facilities (13) 2 (22) 4  
Income before income taxes 2,370 2,418 7,151 7,160  
Assets 63,452   63,452   $ 60,720
Operating Segments [Member]          
Segment Reporting Information [Line Items]          
Adjusted segment EBITDA 4,323 4,267 12,814 12,480  
Eliminations and Reconciling Items [Member]          
Segment Reporting Information [Line Items]          
Corporate and Other 405 397 1,067 1,028  
Depreciation and amortization 954 889 2,828 2,612  
Interest expense 607 561 1,790 1,676  
Losses (gains) on sales of facilities (13) 2 (22) 4  
Income before income taxes 2,370 2,418 7,151 7,160  
National Group [Member] | Operating Segments [Member]          
Segment Reporting Information [Line Items]          
Revenues 5,738 5,525 16,310 15,790  
Salaries and benefits 2,031 1,970 5,962 5,848  
Supplies 779 742 2,315 2,238  
Other operating expenses 1,449 1,466 4,113 3,954  
Equity in earnings of affiliates (1) (1) (2) (1)  
Operating expenses 4,258 4,177 12,388 12,039  
Adjusted segment EBITDA 1,480 1,348 3,922 3,751  
Depreciation and amortization 239 226 713 675  
Assets 13,950   13,950   13,596
Atlantic Group [Member] | Operating Segments [Member]          
Segment Reporting Information [Line Items]          
Revenues 6,421 6,142 20,357 18,431  
Salaries and benefits 2,347 2,288 6,926 6,750  
Supplies 916 889 2,794 2,738  
Other operating expenses 1,870 1,627 6,085 4,793  
Equity in earnings of affiliates 0 (1) (2) (3)  
Operating expenses 5,133 4,803 15,803 14,278  
Adjusted segment EBITDA 1,288 1,339 4,554 4,153  
Depreciation and amortization 304 281 900 830  
Assets 18,467   18,467   17,945
American Group [Member] | Operating Segments [Member]          
Segment Reporting Information [Line Items]          
Revenues 6,848 6,688 19,996 19,512  
Salaries and benefits 2,356 2,275 6,920 6,687  
Supplies 1,047 1,053 3,190 3,140  
Other operating expenses 1,907 1,796 5,597 5,156  
Equity in earnings of affiliates (17) (16) (49) (47)  
Operating expenses 5,293 5,108 15,658 14,936  
Adjusted segment EBITDA 1,555 1,580 4,338 4,576  
Depreciation and amortization 296 283 887 839  
Assets 21,846   21,846   21,217
Corporate and Other [Member]          
Segment Reporting Information [Line Items]          
Revenues 842 806 2,525 2,354  
Depreciation and amortization 115 $ 99 328 $ 268  
Assets $ 9,189   $ 9,189   $ 7,962