Condensed, Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014
Cash flows from operating activities:
Net income	[1]	$ 151,944	$ 110,774
Adjustments to reconcile net income to net cash provided by operating activities:
Impairment of goodwill and other long-lived assets		0	27,019
Depreciation and amortization		60,634	59,659
Amortization of debt issue costs		1,306	957
Provision for uncollectible accounts		6,723	4,388
Debt retirement costs		0	1,709
Net gain on sale or disposal of assets		(234)	(173)
Share-based compensation		12,086	12,234
Excess tax benefits from stock based compensation		(8,008)	(3,808)
Other		(431)	381
Changes in operating assets and liabilities:
Trade accounts receivable		(20,568)	(9,678)
Inventory, prepaid expenses and other assets		(931)	(8,233)
Accounts payable and other accrued liabilities		(2,451)	2,920
Accrued payroll and related liabilities		18,892	14,761
Income taxes		28,054	12,137
Net cash provided by operating activities		247,016	225,047
Cash flows from investing activities:
Business acquisitions, net of cash acquired		(119,336)	(65,415)
Property and equipment additions		(61,470)	(50,093)
Proceeds from sale or disposal of assets		6,469	4,464
Other		(434)	(202)
Net cash used in investing activities		(174,771)	(111,246)
Cash flows from financing activities:
Repayment of long-term obligations		(20,174)	(563,976)
Proceeds from issuance of long-term obligations		0	600,000
Proceeds from revolving credit facility		97,000	0
Payment of financing costs		0	(7,987)
Distributions to noncontrolling interest partners		(3,810)	(3,577)
Purchase of noncontrolling interests		(1,493)	(326)
Proceeds from issuance of common stock under stock incentive plans		1,571	926
Excess tax benefits from stock based compensation		8,008	3,808
Stock repurchases		(161,117)	(139,910)
Other		2,210	(838)
Net cash used in financing activities		(77,805)	(111,880)
Effect of currency exchange rate changes on cash and cash equivalents		(831)	(443)
(Decrease) increase in cash and cash equivalents		(6,391)	1,478
Cash and cash equivalents at beginning of period		81,383	125,029
Cash and cash equivalents at end of period		74,992	126,507
Supplemental disclosures of cash flow information:
Interest paid		13,674	10,633
Income taxes paid		67,814	57,108
Detail of acquisitions:
Fair value of assets acquired and liabilities assumed		138,160	79,979
Fair value of pre-existing investment		0	(2,014)
Noncontrolling interest		0	(1,705)
Cash paid for acquisitions, net of acquired cash		(119,336)	(65,415)
Assumed debt		(12,402)	(4,483)
Contingent consideration		(476)	(2,531)
Holdbacks		(4,497)	(2,900)
Liabilities assumed		$ 1,449	$ 931

[1] Includes approximately $2.5 million and $1.9 million of net income related to redeemable and mandatorily redeemable noncontrolling interests for the nine months ended September 30, 2015 and 2014, respectively.