Financial Commitments (Details) (USD $)	12 Months Ended											3 Months Ended			0 Months Ended	1 Months Ended					12 Months Ended			1 Months Ended			12 Months Ended		12 Months Ended		1 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended		12 Months Ended				12 Months Ended						12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Construction Equipment, Vehicles and Office Space [Member]	Dec. 31, 2011 Construction Equipment, Vehicles and Office Space [Member]	Dec. 31, 2010 Construction Equipment, Vehicles and Office Space [Member]	Dec. 31, 2012 Revolving Credit Facility [Member]	Aug. 02, 2012 Revolving Credit Facility [Member]	Mar. 31, 2012 Revolving Credit Facility [Member]	Dec. 31, 2011 Revolving Credit Facility [Member]	Aug. 03, 2011 Revolving Credit Facility [Member]	Jun. 30, 2011 Frontier Kempner [Member]	Jun. 01, 2011 Frontier Kempner [Member]	Dec. 31, 2012 Swap [Member]	Oct. 20, 2010 Senior Notes [Member]	Apr. 30, 2011 Senior Notes [Member] D	Dec. 31, 2012 Senior Notes [Member]	Dec. 31, 2011 Senior Notes [Member]	Dec. 31, 2012 Revolving Credit Facility [Member]	Dec. 31, 2011 Revolving Credit Facility [Member]	Dec. 31, 2012 Term Loan [Member]	Dec. 31, 2011 Term Loan [Member]	Aug. 03, 2011 Term Loan [Member]	Sep. 30, 2011 Equipment Financing [Member] Loan Contract	Aug. 31, 2011 Equipment Financing [Member]	Mar. 31, 2011 Equipment Financing [Member]	Dec. 31, 2012 Equipment Financing [Member]	Dec. 31, 2011 Equipment Financing [Member]	Dec. 31, 2012 Transportation Equipment Loan at Fixed Rate [Member]	Dec. 31, 2011 Transportation Equipment Loan at Fixed Rate [Member]	Jan. 31, 2012 Promissory Note to Purchase Real Estate [Member]	Dec. 31, 2012 Promissory Note to Purchase Real Estate [Member] Installment	Jun. 30, 2011 Lunda Seller Notes [Member]	Dec. 31, 2012 Lunda Seller Notes [Member]	Dec. 31, 2011 Lunda Seller Notes [Member]	Dec. 31, 2012 Transportation Equipment Loan at Variable Rate [Member]	Dec. 31, 2011 Transportation Equipment Loan at Variable Rate [Member]	Dec. 31, 2012 Land and Office Building Mortgages [Member]	Dec. 31, 2011 Land and Office Building Mortgages [Member]	Dec. 31, 2012 Land Mortgages [Member]	Dec. 31, 2012 Office Building Mortgages [Member]	Dec. 31, 2012 Office Building Mortgages at Variable Rate [Member]	Dec. 31, 2011 Office Building Mortgages at Variable Rate [Member]	Dec. 31, 2012 Office Building Mortgages at Fixed Rate 1 [Member]	Dec. 31, 2011 Office Building Mortgages at Fixed Rate 1 [Member]	Dec. 31, 2012 Office Building Mortgages at Fixed Rate 2 [Member]	Dec. 31, 2011 Office Building Mortgages at Fixed Rate 2 [Member]	Dec. 31, 2012 Other Indebtedness [Member]	Dec. 31, 2011 Other Indebtedness [Member]	Dec. 30, 2011 Frontier Kempner Seller Notes [Member] Frontier Kempner [Member]	Jun. 01, 2011 Frontier Kempner Seller Notes [Member] Frontier Kempner [Member]	Jun. 30, 2011 GreenStar Seller Notes [Member] GreenStar Services Corporation [Member]
Debt Instrument [Line Items]
Long-term debt, gross																	$ 300,000,000	$ 300,000,000
Unamortized debt discount															(2,200,000)		(1,742,000)	(1,972,000)
Total long term-debt, net of unamortized debt discount	737,090,000	672,507,000															298,258,000	298,028,000	120,000,000	0	152,500,000	185,000,000					80,297,000	100,558,000	30,905,000	32,145,000				21,750,000	21,750,000	14,087,000	14,774,000	7,599,000	8,246,000			3,915,000	4,159,000	1,750,000	0	1,111,000	1,189,000	4,918,000	6,658,000
Less - current maturities	(67,710,000)	(59,959,000)
Long-term debt, net	669,380,000	612,548,000
Maturity date															Nov. 01, 2018																		Jul. 01, 2016
Interest rate (in hundredths)																	7.625%							2.53%					6.44%		0.20%			5.00%				5.25%						0.20%		5.62%					2.00%	8.00%
Imputed interest rate (in hundredths)																	7.75%
Interest rate, minimum (in hundredths)																											2.21%
Interest rate, maximum (in hundredths)																											3.98%
Term of debt																					5 years						5 years		5 years					5 years		7 years				7 years	15 years	10 years		5 years		5 years
Balloon payments																											8,800,000		29,200,000		1,500,000					12,100,000				3,000,000		2,600,000		1,500,000		1,100,000
Description of variable rate basis																																				LIBOR				LIBOR	LIBOR	Lender's Prime Rate
Basis spread on variable rate (in hundredths)																																				2.40%				2.00%	2.00%	0.00%
Variable interest rate (in hundredths)																																										3.25%	1.00%
Principal payments required under long-term debt obligations [Abstract]
2013	67,700,000
2014	94,300,000
2015	82,000,000
2016	190,100,000
2017	300,000
2018 and beyond	302,700,000
Private placement offering price (in hundredths)															99.258%
Proceeds from the placement of Senior Notes	0	0	297,774,000												293,200,000
Debt issuance costs															4,600,000
Maximum redemption percentage of aggregate principal amount of Senior Notes (in hundredths)															35.00%
Redemption price, percentage of principal amount at any time prior to November 1, 2013 (in hundredths)															107.625%
Redemption price, percentage of principal amount at any time prior to November 1, 2014 (in hundredths)															100.00%
Redemption price, change of control triggering event (in hundredths)															101.00%
Default, minimum percentage of principal amount of Senior Notes held (in hundredths)															25.00%
Minimum number of days for open Exchange Offer																30
Face amount																					200,000,000		200,000,000
Maximum adjustment to Applicable Rate (in hundredths)														0.975%
Debt assumed in acquisition													52,000,000
Repayment of assumed debt												35,000,000
Promissory note payable													17,100,000																																					14,100,000		74,900,000
Number of equipment financing agreements																								2
Number of loans obtained																								2
Loans obtained during the period																								12,500,000	25,000,000	59,700,000					2,100,000
Loans repaid during the period																										27,400,000
Number of equal monthly installments of principal and interest																																24
Amended Credit Agreement [Abstract]
Maximum borrowing capacity											300,000,000
Original sublimit for letters of credit											50,000,000
Amended sublimit for letters of credit								150,000,000
Percentage of consolidated net worth that is factored into consolidated net worth covenant (in hundredths)									85.00%
Maximum goodwill and intangible assets impairment charge added back to covenants							450,000,000
Percentage of net income for each fiscal quarter (with no deduction for net losses) factored into consolidated net worth covenant (in hundredths)							50.00%
Percentage of aggregate amount of all equity issuances that increase stockholder's equity factored into consolidated net worth covenant (in hundredths)							100.00%
Minimum fixed charge ratio, quarter ending September 30, 2012 (in hundredths)								1.00
Minimum fixed charge ratio, quarter ending December 30, 2012 (in hundredths)								1.00
Minimum fixed charge ratio, quarter ending March 31, 2013 (in hundredths)								1.10
Minimum fixed charge ratio, quarter ending June 30, 2013 (in hundredths)								1.10
Minimum fixed charge ratio, quarter ending September 30, 2013 and thereafter (in hundredths)								1.25
Maximum consolidated leverage ratio, quarter ending September 30, 2012 (in hundredths)								4.25
Maximum consolidated leverage ratio, quarter ending December 31, 2012 (in hundredths)								4.25
Maximum consolidated leverage ratio, quarter ending March 31, 2013 (in hundredths)								4.25
Maximum consolidated leverage ratio, quarter ending June 30, 2013 (in hundredths)								3.75
Maximum consolidated leverage ratio, quarter ending September 30, 2013 (in hundredths)								3.75
Maximum consolidated leverage ratio, quarter ending December 31, 2013 (in hundredths)								3.75
Maximum consolidated leverage ratio, quarter ending March 31, 2014 (in hundredths)								3.25
Maximum consolidated leverage ratio, quarter ending June 30, 2014 (in hundredths)								3.25
Maximum consolidated leverage ratio, quarter ending September 30, 2014 (in hundredths)								3.25
Maximum consolidated leverage ratio, quarter ending December 31, 2014 and thereafter (in hundredths)								2.75
Minimum adjustment to British Bankers Association LIBOR rate (in hundredths)								2.00%
Maximum adjustment to British Bankers Association LIBOR rate (in hundredths)								4.00%
Maximum adjustment to Federal Funds rate (in hundredths)								0.50%
Maximum adjustment to Bank of America, N.A. prime rate (in hundredths)								3.00%
Minimum commitment fee percentage (in hundredths)								0.375%
Maximum commitment fee percentage (in hundredths)								0.70%
Outstanding borrowings							120,000,000			0
Letters of credit outstanding							200,000			3,000,000
Available borrowing capacity							179,800,000
Operating leases, future minimum rent payments [Abstract]
2013				15,182,000
2014				12,142,000
2015				9,475,000
2016				5,147,000
2017				2,799,000
Thereafter				3,258,000
Subtotal				48,003,000
Less - Sublease rental agreements				(1,230,000)
Operating leases, future minimum rent payments less sublease rental agreements				46,773,000
Operating leases, rent expense [Abstract]
Operating leases, rent expense				$ 17,730,000	$ 15,866,000	$ 10,546,000