Supplemental Guarantor Condensed Consolidating Financial Information - Condensed Statement of Cash Flow (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Cash Flows from Operating Activities:
Net cash provided by (used for) operating activities	$ 15,400	$ 35,550
Cash Flows from Investing Activities:
Capital expenditures	(36,440)	(23,520)
Acquisition of businesses, net of cash acquired	(84,600)	(28,620)
Net proceeds from disposition of assets	2,950	2,240
Net Cash Provided by (Used in) Investing Activities	(118,090)	(49,900)
Cash Flows from Financing Activities:
Proceeds from sale of common stock	79,040	0
Proceeds from borrowings on term loan facilities	140,370	226,520
Repayments of borrowings on term loan facilities	(130,850)	(250,170)
Proceeds from borrowings on revolving credit facilities and accounts receivable facility	555,300	551,900
Repayments of Lines of Credit	555,300	547,020
Payments of Financing Costs		6,680
Shares surrendered upon vesting of options and restricted stock awards to cover tax obligations	(990)	(830)
Proceeds from exercise of stock options	5,680	960
Excess tax benefits from stock based compensation	2,310	3,840
Proceeds from Contributions from Affiliates	0	0
Repurchase of senior secured notes	(50,000)	0
Senior secured notes redemption premium	(4,880)
Distributions to noncontrolling interests	(820)	0
Net Cash Provided by (Used in) Financing Activities	39,860	(21,480)
Cash and Cash Equivalents:
(Decrease) Increase for the period	(62,830)	(35,830)
At beginning of period	88,920	46,370
At end of period	26,090	10,540
Parent [Member]
Cash Flows from Operating Activities:
Net cash provided by (used for) operating activities	(12,170)	(12,190)
Cash Flows from Investing Activities:
Capital expenditures	0	0
Acquisition of businesses, net of cash acquired	0	0
Net proceeds from disposition of assets	0	0
Net Cash Provided by (Used in) Investing Activities	0	0
Cash Flows from Financing Activities:
Proceeds from sale of common stock	79,040
Proceeds from borrowings on term loan facilities	0	0
Repayments of borrowings on term loan facilities	0	0
Proceeds from borrowings on revolving credit facilities and accounts receivable facility	0	0
Repayments of Lines of Credit	0	0
Payments of Financing Costs		0
Shares surrendered upon vesting of options and restricted stock awards to cover tax obligations	(990)	(830)
Proceeds from exercise of stock options	5,680	960
Excess tax benefits from stock based compensation	0	0
Proceeds from Contributions from Affiliates	(16,680)	12,060
Repurchase of senior secured notes	(50,000)
Senior secured notes redemption premium	(4,880)
Distributions to noncontrolling interests	0
Net Cash Provided by (Used in) Financing Activities	12,170	12,190
Cash and Cash Equivalents:
(Decrease) Increase for the period	0	0
At beginning of period	0	0
At end of period	0	0
Guarantor [Member]
Cash Flows from Operating Activities:
Net cash provided by (used for) operating activities	26,100	29,050
Cash Flows from Investing Activities:
Capital expenditures	(23,600)	(14,950)
Acquisition of businesses, net of cash acquired	(62,730)	(27,200)
Net proceeds from disposition of assets	2,790	2,190
Net Cash Provided by (Used in) Investing Activities	(83,540)	(39,960)
Cash Flows from Financing Activities:
Proceeds from sale of common stock	0
Proceeds from borrowings on term loan facilities	0	225,000
Repayments of borrowings on term loan facilities	(6,610)	(249,510)
Proceeds from borrowings on revolving credit facilities and accounts receivable facility	555,300	551,900
Repayments of Lines of Credit	555,300	547,020
Payments of Financing Costs		6,680
Shares surrendered upon vesting of options and restricted stock awards to cover tax obligations	0	0
Proceeds from exercise of stock options	0	0
Excess tax benefits from stock based compensation	2,310	3,840
Proceeds from Contributions from Affiliates	34,600	18,430
Repurchase of senior secured notes	0
Senior secured notes redemption premium	0
Distributions to noncontrolling interests	(820)
Net Cash Provided by (Used in) Financing Activities	29,480	(4,040)
Cash and Cash Equivalents:
(Decrease) Increase for the period	(27,960)	(14,950)
At beginning of period	33,820	15,070
At end of period	5,860	120
Non-Guarantor [Member]
Cash Flows from Operating Activities:
Net cash provided by (used for) operating activities	1,470	18,690
Cash Flows from Investing Activities:
Capital expenditures	(12,840)	(8,570)
Acquisition of businesses, net of cash acquired	(21,870)	(1,420)
Net proceeds from disposition of assets	160	50
Net Cash Provided by (Used in) Investing Activities	(34,550)	(9,940)
Cash Flows from Financing Activities:
Proceeds from sale of common stock	0
Proceeds from borrowings on term loan facilities	140,370	1,520
Repayments of borrowings on term loan facilities	(124,240)	(660)
Proceeds from borrowings on revolving credit facilities and accounts receivable facility	0	0
Repayments of Lines of Credit	0	0
Payments of Financing Costs		0
Shares surrendered upon vesting of options and restricted stock awards to cover tax obligations	0	0
Proceeds from exercise of stock options	0	0
Excess tax benefits from stock based compensation	0	0
Proceeds from Contributions from Affiliates	(17,920)	(30,490)
Repurchase of senior secured notes	0
Senior secured notes redemption premium	0
Distributions to noncontrolling interests	0
Net Cash Provided by (Used in) Financing Activities	(1,790)	(29,630)
Cash and Cash Equivalents:
(Decrease) Increase for the period	(34,870)	(20,880)
At beginning of period	55,100	31,300
At end of period	20,230	10,420
Eliminations [Member]
Cash Flows from Operating Activities:
Net cash provided by (used for) operating activities	0	0
Cash Flows from Investing Activities:
Capital expenditures	0	0
Acquisition of businesses, net of cash acquired	0	0
Net proceeds from disposition of assets	0	0
Net Cash Provided by (Used in) Investing Activities	0	0
Cash Flows from Financing Activities:
Proceeds from sale of common stock	0
Proceeds from borrowings on term loan facilities	0	0
Repayments of borrowings on term loan facilities	0	0
Proceeds from borrowings on revolving credit facilities and accounts receivable facility	0	0
Repayments of Lines of Credit	0	0
Payments of Financing Costs		0
Shares surrendered upon vesting of options and restricted stock awards to cover tax obligations	0	0
Proceeds from exercise of stock options	0	0
Excess tax benefits from stock based compensation	0	0
Proceeds from Contributions from Affiliates	0	0
Repurchase of senior secured notes	0
Senior secured notes redemption premium	0
Distributions to noncontrolling interests	0
Net Cash Provided by (Used in) Financing Activities	0	0
Cash and Cash Equivalents:
(Decrease) Increase for the period	0	0
At beginning of period	0	0
At end of period	$ 0	$ 0