CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 3,055	$ 34,044
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation	27,807	26,308
Amortization	16,550	17,007
Asset impairment		3,715
Provision for share based compensation	3,190	133
Deferred income tax expense	4,343	11,518
Amortization of deferred financing costs	4,654	3,393
Other	27	79
Changes in operating assets and liabilities, net of business acquisitions:
Accounts receivable	5,049	(33,524)
Other assets	(16,214)	(25,401)
Accounts payable	(7,711)	18,489
Accrued wages and benefits	21,224	10,956
Accrued subordinated debt call premium	16,502
Accrued interest	20,871	8,732
Other liabilities and income tax payable	(681)	16,214
Net cash flows from operating activities	98,666	91,663
CASH FLOWS USED IN INVESTING ACTIVITIES:
Business acquisitions, net of cash acquired of $0 and $1,350	(13)	(76,579)
Purchases of property and equipment	(33,542)	(34,073)
Other	(408)
Net cash flows used in investing activities	(33,963)	(110,652)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from initial public offering, net of offering costs	400,464
Proceeds from revolving credit facilities	50,000	71,100
Payments on revolving credit facilities		(47,200)
Payment of deferred financing and other debt-related costs	(29,972)	(7)
Principal repayments on long-term obligations	(10,062)	(3,856)
Proceeds and net settlements from stock options exercised including excess tax benefits	(689)	300
Dividends paid	(158)
Repurchase of common stock		(51)
Other	(2)	(20)
Net cash flows from (used in) financing activities	409,581	20,266
EFFECT OF EXCHANGE RATES ON CASH AND CASH EQUIVALENTS	(2,259)	2,748
NET CHANGE IN CASH AND CASH EQUIVALENTS	472,025	4,025
CASH AND CASH EQUIVALENTS, Beginning of period	179,111	93,836
CASH AND CASH EQUIVALENTS, End of period	651,136	97,861
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash paid during the period for interest	47,248	50,778
Cash paid during the period for income taxes, net of refunds of $114 and $1,733	16,195	16,907
SUPPLEMENTAL DISCLOSURE OF NONCASH INVESTING ACTIVITIES:
Accrued obligations for the purchase of property and equipment	$ 8,224	$ 5,329