Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash Flows from Operating Activities:
Net income	$ 634,261	$ 546,277
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation & amortization	335,002	334,127
Stock-based compensation expense	50,645	42,838
Gain on sale of assets and businesses	(2,513)	0
Changes in assets & liabilities, net of effects from acquisitions and dispositions:
Accounts receivable	(74,129)	10,090
Accrued interest	(5,808)	(5,747)
Accrued and deferred income taxes	(53,165)	(20,177)
Other working capital accounts	89,157	23,729
Other assets and deferred charges	(37,133)	(21,346)
Other	23,008	(54,664)
Accrued insurance expense, net of commercial premiums paid	69,386	80,814
Payments made in settlement of self-insurance claims	(53,223)	(57,224)
Net cash provided by operating activities	975,488	878,717
Cash Flows from Investing Activities:
Property and equipment additions, net of disposals	(521,349)	(418,693)
Acquisition of property and businesses	(108,016)	(19,610)
Proceeds received from sales of assets and businesses	13,502	0
Costs incurred for purchase and implementation of information technology applications	(25,487)	(26,401)
Decrease (increase) in capital reserves of commercial insurance subsidiary	100	(3,000)
Investment in, and advances to, joint venture	(13,910)	0
Net cash used in investing activities	(655,160)	(467,704)
Cash Flows from Financing Activities:
Reduction of long-term debt	(99,969)	(143,526)
Additional borrowings	82,400	43,124
Financing costs	(774)	(34)
Repurchase of common shares	(261,256)	(242,870)
Dividends paid	(28,086)	(28,776)
Issuance of common stock	7,737	7,637
Profit distributions to noncontrolling interests	(8,243)	(15,924)
Net cash used in financing activities	(308,191)	(380,369)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(1,742)	1,485
Increase in cash, cash equivalents and restricted cash	10,395	32,129
Cash, cash equivalents and restricted cash, beginning of period	167,297	121,950
Cash, cash equivalents and restricted cash, end of period	177,692	154,079
Supplemental Disclosures of Cash Flow Information:
Interest paid	114,162	107,442
Income taxes paid, net of refunds	247,486	305,885
Noncash purchases of property and equipment	$ 88,932	$ 64,958