Condensed, Consolidated Statements of Cash Flows (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Cash flows from operating activities:
Net income	$ 39,553	[1]	$ 34,915	[1]
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	19,797		19,767
Amortization of debt issue costs	434		304
Provision for uncollectible accounts	1,183		890
Net loss (gain) on sale or disposal of assets	335		(1,221)
Share-based compensation	4,132		4,544
Excess tax benefits from stock based compensation	(791)		(392)
Other	(989)		(905)
Changes in operating assets and liabilities:
Trade accounts receivable	(14,570)		(5,825)
Inventory, prepaid expenses and other assets	2,862		(1,389)
Accounts payable and other accrued liabilities	(6,954)		(3,773)
Accrued payroll and related liabilities	14,052		6,247
Income taxes	21,581		15,165
Net cash provided by operating activities	80,625		68,327
Cash flows from investing activities:
Business acquisitions, net of cash acquired	(32,150)		(17,295)
Real estate acquired in connection with business acquisitions	(1,502)		0
Property and equipment additions	(16,526)		(16,619)
Proceeds from sale or disposal of assets	92		859
Other	(576)		520
Net cash used in investing activities	(50,662)		(32,535)
Cash flows from financing activities:
Repayment of long-term obligations	(5,165)		(12,806)
Distributions to noncontrolling interest partners	(1,325)		(1,090)
Purchase of noncontrolling interests	(1,483)		(326)
Proceeds from issuance of common stock under stock incentive plans	404		372
Excess tax benefits from stock based compensation	791		392
Stock repurchases	(44,845)		(9,793)
Other	(80)		0
Net cash used in financing activities	(51,703)		(23,251)
Effect of currency exchange rate changes on cash and cash equivalents	(365)		(282)
(Decrease) increase in cash and cash equivalents	(22,105)		12,259
Cash and cash equivalents at beginning of period	81,383		125,029
Cash and cash equivalents at end of period	59,278		137,288
Supplemental disclosures of cash flow information:
Interest paid	4,482		3,708
Income taxes paid	3,077		6,853
Detail of acquisitions:
Fair value of assets acquired	38,490		18,550
Noncontrolling interest	0		(855)
Cash paid for acquisitions, net of acquired cash	(32,150)		(17,295)
Assumed debt	(4,446)		0
Holdbacks	(1,722)		(400)
Liabilities assumed	$ 172		$ 0

[1] Includes approximately $0.8 million and $0.5 million of net income related to redeemable and mandatorily redeemable noncontrolling interests for the three months ended March 31, 2015 and 2014, respectively.