Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Cash flows from operating activities:
Net income	$ 99,860	[1]	$ 114,158	[1]	$ 135,586	[1]
Adjustments to reconcile net income to net cash provided by operating activities:
Goodwill impairment	21,310
Depreciation and amortization	56,988		46,069		39,571
Amortization of debt issue costs	1,445		862		486
Provision for uncollectible accounts	6,742		7,366		7,048
Debt retirement costs	2,764		2,131
Net loss on sale of assets	382		374		4,035
Share-based compensation	10,773		9,340		7,951
Deferred income taxes	19,552		13,493		24,600
Excess tax benefit from exercise of stock options	(1,708)		(378)		(866)
Other	(637)		(901)		(425)
Changes in operating assets and liabilities:
Trade accounts receivable	(14,107)		(7,048)		(10,004)
Inventory, prepaid expenses and other assets	(12,297)		(11,868)		(15,591)
Accounts payable and other accrued liabilities	(5,415)		7,463		(1,974)
Accrued payroll and related liabilities	4,583		(385)		(7,794)
Income taxes	816		(12,603)		848
Net cash provided by operating activities	191,051		168,073		183,471
Cash flows from investing activities:
Business acquisitions, net of cash acquired	(205,794)		(79,851)		(74,567)
Real estate acquired in connection with business acquisitions	(1,900)		(9,289)		(4,894)
Property and equipment additions	(63,485)		(61,951)		(50,801)
Proceeds from sale of assets	465		939		151
Other	(596)		(22)		(649)
Net cash used in investing activities	(271,310)		(150,174)		(130,760)
Cash flows from financing activities:
Repayment of debt	(98,990)		(555,529)		(7,936)
Proceeds from the issuance of long-term debt	150,000		500,000
Payment of financing costs	(2,944)		(9,112)
Proceeds from revolving credit facility	50,000
Repayment of revolving credit facility	(50,000)
Distributions to noncontrolling interest partners	(3,277)		(4,247)		(4,189)
Proceeds from issuance of common stock under stock incentive plans	3,999		5,510		15,297
Excess tax benefits from exercise of stock options	1,708		378		866
Stock repurchases	(2,673)		(2,310)		(561)
Other	(819)		(832)		(10)
Net cash provided by (used in) financing activities	47,004		(66,142)		3,467
Effect of currency exchange rate changes on cash and cash equivalents	(220)		188		44
(Decrease) increase in cash and cash equivalents	(33,475)		(48,055)		56,222
Cash and cash equivalents at beginning of year	97,126		145,181		88,959
Cash and cash equivalents at end of year	63,651		97,126		145,181
Supplemental disclosures of cash flow information:
Interest paid	15,088		13,357		22,064
Income taxes paid	55,660		77,210		59,132
Detail of acquisitions:
Fair value of assets acquired	254,781		139,085		94,518
Cash paid for acquisitions	(203,996)		(79,851)		(74,567)
Cash paid to bondholders/ debt holders	(26,048)		(29,532)
Non-cash note conversion to equity interest in subsidiary					(5,700)
Contingent consideration	(560)		(259)		(712)
Holdbacks	(1,500)
Liabilities assumed	$ 22,677		$ 29,443		$ 13,539

[1] Includes $2.0 million, $1.2 million and $1.1 million for 2011, 2010 and 2009, respectively, related to redeemable and mandatorily redeemable noncontrolling interests.