Consolidated Statements of Cash Flows (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures	$ 17,233,000	$ 9,533,000	$ 3,999,000
Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation	3,446,000	2,868,000	1,708,000
Adjustments Related to Tax Withholding for Share-based Compensation		8,216,000	2,673,000
Stock Issued During Period, Value, Acquisitions	0	(10,500,000)	0
Capital Lease Obligations Incurred	21,668,000	0	0
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability	(1,285,000)	(1,306,000)	(560,000)
Cash flows from operating activities:
Net income	142,922,000	50,716,000	99,860,000
Adjustments to reconcile net income to net cash provided by operating activities:
Asset Impairment Charges	0
Goodwill and Intangible Asset Impairment		123,573,000
Goodwill, Impairment Loss		99,501,000	21,310,000
Depreciation and amortization	77,409,000	76,227,000	56,988,000
Amortization of debt issue costs	(1,245,000)	(1,278,000)	(1,445,000)
Provision for uncollectible accounts	7,360,000	6,396,000	6,742,000
Debt retirement costs	0	0	2,764,000
Business Combination, Step Acquisition, Equity Interest in Acquiree, Remeasurement Gain	0	(5,719,000)	0
Net loss on sale of assets	2,455,000	1,310,000	382,000
Share-based compensation	14,104,000	14,087,000	10,773,000
Deferred income taxes	(18,064,000)	33,398,000	(19,552,000)
Excess tax benefit from exercise of stock options	(3,446,000)	(2,868,000)	(1,708,000)
Other	(377,000)	(584,000)	(637,000)
Changes in operating assets and liabilities:
Trade accounts receivable	11,048,000	(1,640,000)	14,107,000
Inventory, prepaid expenses and other assets	(7,134,000)	(10,329,000)	(12,297,000)
Accounts payable and other accrued liabilities	(557,000)	(3,640,000)	5,415,000
Accrued payroll and related liabilities	(6,502,000)	(7,181,000)	(4,583,000)
Income taxes	(7,759,000)	(4,103,000)	(816,000)
Net Cash Provided by (Used in) Operating Activities	256,372,000	237,253,000	191,051,000
Cash flows from investing activities:
Real estate acquired in connection with business acquisitions	(5,328,000)	(5,337,000)	(1,900,000)
Property and equipment additions	(73,270,000)	(76,807,000)	(63,485,000)
Proceeds from sale of assets	(7,096,000)	(115,000)	(465,000)
Other	(2,541,000)	(2,313,000)	(596,000)
Net cash used in investing activities	(126,731,000)	(219,258,000)	(271,310,000)
Cash flows from financing activities:
Repayment of debt	(41,129,000)	(60,775,000)	(98,990,000)
Proceeds from the issuance of long-term debt	0	50,000,000	150,000,000
Payment of financing costs	0	(122,000)	(2,944,000)
Proceeds from revolving credit facility	0	50,000,000	50,000,000
Repayment of revolving credit facility	0	(50,000,000)	(50,000,000)
Distributions to noncontrolling interest partners	(4,866,000)	(4,481,000)	(3,277,000)
Payments to Acquire Additional Interest in Subsidiaries	(6,581,000)	0	0
Proceeds from issuance of common stock under stock incentive plans	17,233,000	9,533,000	3,999,000
Excess tax benefits from exercise of stock options	3,446,000	2,868,000	1,708,000
Payments for Repurchase of Common Stock	39,367,000	8,159,000	2,673,000
Other	749,000	2,378,000	819,000
Net cash provided by (used in) financing activities	(72,013,000)	(13,514,000)	47,004,000
Effect of currency exchange rate changes on cash and cash equivalents	(1,034,000)	303,000	(220,000)
(Decrease) increase in cash and cash equivalents	56,594,000	4,784,000	(33,475,000)
Cash and cash equivalents at beginning of year	68,435,000	63,651,000	97,126,000
Cash and cash equivalents at end of year	125,029,000	68,435,000	63,651,000
Supplemental disclosures of cash flow information:
Interest paid	16,422,000	15,407,000	15,088,000
Income taxes paid	61,825,000	61,481,000	55,660,000
Detail of acquisitions:
Fair value of assets acquired	75,445,000	220,526,000	254,781,000
Holdbacks	(1,092,000)	(3,475,000)	(1,500,000)
Liabilities assumed	11,084,000	24,403,000	22,677,000
Business Combination, Step Acquisition, Equity Interest in Acquiree, Fair Value	0	(11,850,000)	0
Noncontrolling Interest, Increase from Business Combination	(3,336,000)	8,161,000	0
Payments to Acquire Businesses, Net of Cash Acquired	(52,688,000)	(134,916,000)	(205,794,000)
payments to acquire businesses, net of cash acquired and prior year acquisition adjustments			203,996,000
Noncash or Part Noncash Acquisition, Debt Assumed	(2,360,000)	(25,915,000)	(26,048,000)
Series of Individually Immaterial Business Acquisitions [Member]
Detail of acquisitions:
Noncontrolling Interest, Increase from Business Combination	(6,936,000)	0	0
Payments to Acquire Businesses, Net of Cash Acquired	$ (52,688,000)	$ (78,629,000)	$ (34,243,000)