Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash Flows from Operating Activities:
Net income	$ 827,543	$ 797,883	$ 771,312
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation & amortization	490,392	453,076	447,883
Gains on sales of assets and businesses, net of losses	(7,540)	(2,513)	0
Stock-based compensation expense	69,431	66,581	56,738
Costs related to extinguishment of debt	0	2,727	0
Provision for asset impairment	97,631	49,310	0
Changes in assets & liabilities, net of effects from acquisitions and dispositions:
Accounts receivable	(42,056)	(42,239)	(24,719)
Accrued interest	209	(4,478)	705
Accrued and deferred income taxes	(25,194)	(54,052)	(6,405)
Other working capital accounts	39,664	24,696	(15,165)
Other assets and deferred charges	(27,205)	(31,429)	(27,936)
Other	7,703	(1,536)	21,769
Accrued insurance expense, net of commercial premiums paid	105,672	92,863	102,595
Payments made in settlement of self-insurance claims	(97,781)	(76,147)	(79,192)
Net cash provided by operating activities	1,438,469	1,274,742	1,247,585
Cash Flows from Investing Activities:
Property and equipment additions, net of disposals	(634,095)	(664,962)	(557,506)
Acquisition of property and businesses	(8,005)	(110,464)	(22,878)
(Outflows) Inflows from foreign exchange contracts that hedge our net U.K. investment	(19,763)	66,151	(64,333)
Proceeds received from sales of assets and businesses	9,450	13,502	108
Costs incurred for purchase and implementation of information technology applications	(21,418)	(36,243)	(29,047)
Decrease (Increase) in capital reserves of commercial insurance subsidiary	0	100	(3,100)
Investment in, and advances to, joint venture and other	(14,579)	(15,331)	(7,976)
Net cash used in investing activities	(688,410)	(747,247)	(684,732)
Cash Flows from Financing Activities:
Reduction of long-term debt	(57,142)	(830,496)	(143,106)
Additional borrowings	39,220	791,247	41,100
Financing costs	0	(13,787)	(76)
Repurchase of common shares	(770,504)	(397,425)	(364,401)
Dividends paid	(53,003)	(37,342)	(38,211)
Issuance of common stock	10,806	10,196	10,254
Profit distributions to noncontrolling interests	(15,859)	(14,595)	(24,713)
Capital contributions from minority members	1,446	0	0
Net cash used in financing activities	(845,036)	(492,202)	(519,153)
Effect of exchange rate changes on cash and cash equivalents	959	(2,905)	1,647
(Decrease) Increase in cash and cash equivalents	(94,018)	32,388	45,347
Cash, cash equivalents and restricted cash, beginning of period	199,685	167,297	121,950
Cash, cash equivalents and restricted cash, end of period	105,667	199,685	167,297
Supplemental Disclosures of Cash Flow Information:
Interest paid	157,406	150,293	135,533
Income taxes paid, net of refunds	260,622	293,837	370,855
Noncash purchases of property and equipment	63,514	77,674	82,496
Right-of-use assets obtained in exchange for lease obligations	$ 383,857	$ 0	$ 0