Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash Flows from Operating Activities:
Net income	$ 478,663	$ 459,380
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation & amortization	241,208	222,716
Stock-based compensation expense	34,676	34,716
Gain on sale of assets and businesses	0	(2,513)
Changes in assets & liabilities, net of effects from acquisitions and dispositions:
Accounts receivable	(101,329)	(64,055)
Accrued interest	948	199
Accrued and deferred income taxes	(16,846)	(42,540)
Other working capital accounts	30,082	8,977
Other assets and deferred charges	(1,333)	(14,144)
Other	(49,687)	(3,422)
Accrued insurance expense, net of commercial premiums paid	51,819	46,255
Payments made in settlement of self-insurance claims	(44,115)	(38,606)
Net cash provided by operating activities	624,086	606,963
Cash Flows from Investing Activities:
Property and equipment additions, net of disposals	(323,920)	(370,252)
Acquisition of property and businesses	0	(20,931)
Inflows (outflows) from foreign exchange contracts that hedge our net U.K. investment	53,363	22,298
Proceeds received from sales of assets and businesses	0	13,502
Costs incurred for purchase and implementation of information technology applications	(13,893)	(24,087)
Decrease in capital reserves of commercial insurance subsidiary	0	100
Investment in, and advances to, joint ventures and other	(11,949)	(14,059)
Net cash used in investing activities	(296,399)	(393,429)
Cash Flows from Financing Activities:
Reduction of long-term debt	(28,617)	(82,470)
Additional borrowings	177,200	30,500
Financing costs	0	(754)
Repurchase of common shares	(494,649)	(134,784)
Dividends paid	(17,953)	(18,804)
Issuance of common stock	5,271	4,959
Profit distributions to noncontrolling interests	(11,650)	(7,914)
Net cash used in financing activities	(370,398)	(209,267)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(273)	(1,138)
(Decrease) Increase in cash, cash equivalents and restricted cash	(42,984)	3,129
Cash, cash equivalents and restricted cash, beginning of period	199,685	167,297
Cash, cash equivalents and restricted cash, end of period	156,701	170,426
Supplemental Disclosures of Cash Flow Information:
Interest paid	78,623	70,890
Income taxes paid, net of refunds	145,404	182,130
Noncash purchases of property and equipment	71,923	$ 91,742
Right-of-use assets obtained in exchange for lease obligations	$ 359,329