Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash Flows from Operating Activities:
Net income	$ 656,982	$ 987,632	$ 952,790
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation & amortization	581,861	533,213	510,493
Loss (gain) on sales of assets and businesses	584	(5,170)	1,957
Stock-based compensation expense	85,378	73,686	65,837
Costs related to extinguishment of debt	0	16,831	1,365
Provision for asset impairment	57,550	14,391	0
Changes in assets & liabilities, net of effects from acquisitions and dispositions:
Accounts receivable	(258,338)	(8,873)	(145,901)
Accrued interest	1,835	4,950	(10,028)
Accrued and deferred income taxes	(29,510)	(54,030)	9,593
Other working capital accounts	(146,692)	46,526	124,545
Medicare accelerated payments and deferred CARES Act and other grants	2,391	(698,762)	698,768
Other assets and deferred charges	19,918	(39,337)	(4,555)
Other	(8,676)	(82,075)	109,167
Accrued insurance expense, net of commercial premiums paid	174,723	186,215	159,223
Payments made in settlement of self-insurance claims	(141,983)	(91,502)	(113,085)
Net cash provided by operating activities	996,023	883,695	2,360,169
Cash Flows from Investing Activities:
Property and equipment additions	(734,001)	(855,659)	(731,307)
Acquisition of businesses and property	(20,309)	(105,415)	(52,009)
Inflows (outflows) from foreign exchange contracts that hedge our net U.K. investment	94,913	1,357	(21,740)
Proceeds received from sales of assets and businesses	12,001	25,425	8,168
Costs incurred for purchase and implementation of information technology applications	0	19,726	(2,902)
Decrease (increase) in capital reserves of commercial insurance subsidiary	100	100	(100)
Investment in, and advances to, joint ventures and other	0	0	(2,672)
Net cash used in investing activities	(647,296)	(914,466)	(802,562)
Cash Flows from Financing Activities:
Repayments of long-term debt	(89,367)	(3,037,868)	(962,567)
Additional borrowings	705,321	3,254,974	801,599
Financing costs	(3,164)	(18,770)	(10,300)
Repurchase of common shares	(832,918)	(1,220,875)	(206,719)
Dividends paid	(58,449)	(65,896)	(17,344)
Issuance of common stock	14,068	13,372	12,318
Profit distributions to noncontrolling interests	(5,391)	(7,080)	(19,805)
Purchase (sale) of ownership interests by (from) minority member	(48,500)	13,193	17,959
Net cash used in financing activities	(318,400)	(1,068,950)	(384,859)
Effect of exchange rate changes on cash and cash equivalents	(8,424)	(499)	739
Increase decrease in cash, cash equivalents and restricted cash	21,903	(1,100,220)	1,173,487
Cash, cash equivalents and restricted cash, beginning of period	178,934	1,279,154	105,667
Cash, cash equivalents and restricted cash, end of period	200,837	178,934	1,279,154
Supplemental Disclosures of Cash Flow Information:
Interest paid	120,136	75,607	112,598
Income taxes paid, net of refunds	250,759	362,978	286,247
Noncash purchases of property and equipment	$ 72,064	$ 167,234	$ 74,854