Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Cash Flows from Operating Activities:
Net income	$ 215,719	$ 194,323
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation & amortization	104,049	98,998
Stock-based compensation expense	13,204	10,829
Changes in assets & liabilities, net of effects from acquisitions and dispositions:
Accounts receivable	(79,962)	(96,972)
Accrued interest	688	1,117
Accrued and deferred income taxes	91,131	79,050
Other working capital accounts	98,972	(29,829)
Other assets and deferred charges	(5,803)	(234)
Other	20,911	17,807
Accrued insurance expense, net of commercial premiums paid	22,616	22,748
Payments made in settlement of self-insurance claims	(17,298)	(26,562)
Net cash provided by operating activities	464,227	271,275
Cash Flows from Investing Activities:
Property and equipment additions, net of disposals	(127,214)	(89,276)
Acquisition of property and businesses	(19,543)	(34,500)
Net cash used in investing activities	(146,757)	(123,776)
Cash Flows from Financing Activities:
Reduction of long-term debt	(166,671)	(158,871)
Additional borrowings	14,400	20,800
Financing costs	(44)	0
Repurchase of common shares	(171,042)	(28,767)
Dividends paid	(9,757)	(9,899)
Issuance of common stock	2,331	1,768
Excess income tax benefits related to stock-based compensation	11,002	20,807
Profit distributions to noncontrolling interests	(3,407)	(2,413)
Proceeds received from sale/leaseback of real property	0	12,551
Net cash used in financing activities	(323,188)	(144,024)
Effect of exchange rate changes on cash and cash equivalents	(920)	(466)
(Decrease) increase in cash and cash equivalents	(6,638)	3,009
Cash and cash equivalents, beginning of period	61,228	32,069
Cash and cash equivalents, end of period	54,590	35,078
Supplemental Disclosures of Cash Flow Information:
Interest paid	27,133	27,158
Income taxes paid, net of refunds	9,093	2,876
Noncash purchases of property and equipment	$ 47,374	$ 33,082