Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash Flows from Operating Activities:
Net income	$ 546,277	$ 568,433
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation & amortization	334,127	309,172
Stock-based compensation expense	42,838	36,358
Changes in assets & liabilities, net of effects from acquisitions and dispositions:
Accounts receivable	10,090	(6,836)
Accrued interest	(5,747)	3,303
Accrued and deferred income taxes	(20,177)	12,187
Other working capital accounts	23,729	124,987
Other assets and deferred charges	(21,798)	(11,451)
Other	(54,664)	58,040
Excess income tax benefits related to stock-based compensation	0	36,407
Accrued insurance expense, net of commercial premiums paid	80,814	66,049
Payments made in settlement of self-insurance claims	(57,224)	(60,137)
Net cash provided by operating activities	878,265	1,136,512
Cash Flows from Investing Activities:
Property and equipment additions, net of disposals	(418,693)	(396,163)
Acquisition of property and businesses	(19,610)	(136,221)
Increase in capital reserves of commercial insurance subsidiary	(3,000)	0
Costs incurred for purchase and implementation of information technology application	(26,401)	0
Net cash used in investing activities	(467,704)	(532,384)
Cash Flows from Financing Activities:
Reduction of long-term debt	(143,526)	(814,971)
Additional borrowings	43,124	1,026,000
Acquisition of noncontrolling interests in majority owned businesses	0	(418,000)
Financing costs	(34)	(12,330)
Repurchase of common shares	(242,870)	(297,177)
Dividends paid	(28,776)	(29,197)
Issuance of common stock	7,637	6,379
Profit distributions to noncontrolling interests	(15,924)	(61,053)
Net cash used in financing activities	(380,369)	(600,349)
Effect of exchange rate changes on cash and cash equivalents	1,485	(3,263)
Increase in cash and cash equivalents	31,677	516
Cash and cash equivalents, beginning of period	33,747	61,228
Cash and cash equivalents, end of period	65,424	61,744
Supplemental Disclosures of Cash Flow Information:
Interest paid	107,442	82,883
Income taxes paid, net of refunds	305,885	259,174
Noncash purchases of property and equipment	$ 64,958	$ 45,319