Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash Flows from Operating Activities:
Net income	$ 952,790	$ 827,543	$ 797,883
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation & amortization	510,493	490,392	453,076
Loss (Gain) on sales of assets and businesses, net of losses	1,957	(7,540)	(2,513)
Stock-based compensation expense	65,837	69,431	66,581
Costs related to extinguishment of debt	1,365	0	2,727
Provision for asset impairment	0	97,631	49,310
Changes in assets & liabilities, net of effects from acquisitions and dispositions:
Accounts receivable	(145,901)	(42,056)	(42,239)
Accrued interest	(10,028)	209	(4,478)
Accrued and deferred income taxes	9,593	(25,194)	(54,052)
Other working capital accounts	124,545	39,664	24,696
Other assets and deferred charges	(4,555)	(27,205)	(31,429)
Other	109,167	7,703	(1,536)
Accrued insurance expense, net of commercial premiums paid	159,223	105,672	92,863
Payments made in settlement of self-insurance claims	(113,085)	(97,781)	(76,147)
Net cash provided by operating activities	2,360,169	1,438,469	1,274,742
Medicare accelerated payments and deferred CARES Act and other grants	698,768	0	0
Cash Flows from Investing Activities:
Property and equipment additions, net of disposals	(731,307)	(634,095)	(664,962)
Acquisition of property and businesses	(52,009)	(8,005)	(110,464)
(Outflows) Inflows from foreign exchange contracts that hedge our net U.K. investment	(21,740)	(19,763)	66,151
Proceeds received from sales of assets and businesses	8,168	9,450	13,502
Costs incurred for purchase and implementation of information technology applications	(2,902)	(21,418)	(36,243)
Decrease (Increase) in capital reserves of commercial insurance subsidiary	(100)	0	100
Investment in, and advances to, joint venture and other	(2,672)	(14,579)	(15,331)
Net cash used in investing activities	(802,562)	(688,410)	(747,247)
Cash Flows from Financing Activities:
Reduction of long-term debt	(962,567)	(57,142)	(830,496)
Additional borrowings	801,599	39,220	791,247
Financing costs	(10,300)	0	(13,787)
Repurchase of common shares	(206,719)	(770,504)	(397,425)
Dividends paid	(17,344)	(53,003)	(37,342)
Issuance of common stock	12,318	10,806	10,196
Profit distributions to noncontrolling interests	(19,805)	(15,859)	(14,595)
Purchase of ownership interests by minority member	17,959	1,446	0
Net cash used in financing activities	(384,859)	(845,036)	(492,202)
Effect of exchange rate changes on cash and cash equivalents	739	959	(2,905)
Increase (Decrease) in cash and cash equivalents	1,173,487	(94,018)	32,388
Cash, cash equivalents and restricted cash, beginning of period	105,667	199,685	167,297
Cash, cash equivalents and restricted cash, end of period	1,279,154	105,667	199,685
Supplemental Disclosures of Cash Flow Information:
Interest paid	112,598	157,406	150,293
Income taxes paid, net of refunds	286,247	260,622	293,837
Noncash purchases of property and equipment	$ 74,854	$ 63,514	$ 77,674