Condensed, Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013
Cash flows from operating activities:
Net income	$ 81,823	[1]	$ 75,283	[1]
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	39,797		37,739
Amortization of debt issue costs	604		626
Provision for uncollectible accounts	2,612		3,364
Net (gain) loss on sale or disposal of assets	(643)		1,296
Share-based compensation	8,571		7,419
Deferred income taxes	0		2,868
Excess tax benefit from exercise of stock options	(2,092)		(771)
Other	(53)		(384)
Changes in operating assets and liabilities:
Trade accounts receivable	(8,945)		(17,709)
Inventory, prepaid expense and other assets	(6,610)		(470)
Accounts payable and other accrued liabilities	1,171		4,329
Accrued payroll and related liabilities	3,816		1,886
Income taxes	8,062		12,595
Net cash provided by operating activities	128,113		128,071
Cash flows from investing activities:
Business acquisitions, net of cash acquired	(29,271)		(21,835)
Real estate acquired in connection with business acquisitions	(1,493)		(510)
Capital expenditures	(27,979)		(33,095)
Proceeds from sale or disposal of assets	4,456		595
Other	55		(1,042)
Net cash used in investing activities	(54,232)		(55,887)
Cash flows from financing activities:
Repayment of debt	(26,218)		(17,442)
Distributions to noncontrolling interest partners	(2,259)		(2,234)
Purchase of existing noncontrolling interests	(326)		(5,030)
Proceeds from issuance of common stock under stock option plans	467		4,181
Excess tax benefit from exercise of stock options	2,092		771
Repurchase of common stock	(49,091)		(7,956)
Other	(838)		(99)
Net cash used in financing activities	(76,173)		(27,809)
Effect of currency exchange rate changes on cash and cash equivalents	(202)		(540)
(Decrease) increase in cash and cash equivalents	(2,494)		43,835
Cash and cash equivalents at beginning of period	125,029		68,435
Cash and cash equivalents at end of period	122,535		112,270
Supplemental disclosures of cash flow information:
Interest paid	7,491		8,145
Income taxes paid	42,950		30,082
Detail of acquisitions:
Fair value of assets acquired	32,836		26,473
Noncontrolling interest	(1,705)		(3,600)
Cash paid for acquisitions, net of acquired cash	(29,271)		(21,835)
Assumed debt	(736)		0
Contingent consideration	(374)		(46)
Holdbacks	(750)		(460)
Other Liabilities assumed	0		532
Capital lease additions	$ 0		$ 21,668

[1] Includes approximately $1.2 million and $1.9 million of net income related to redeemable and mandatorily redeemable noncontrolling interests for the six months ended June 30, 2014 and 2013, respectively.