Goodwill and Intangible Assets (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Goodwill
Gross goodwill		$ 1,058,631
Accumulated impairment		(487,985)
Balance at beginning of period	570,646
Goodwill recorded in connection with an acquisition	1,286
Balance at end of period	571,932
Building
Goodwill
Gross goodwill		420,267
Accumulated impairment		(409,765)
Balance at beginning of period		10,502
Balance at end of period	10,502	10,502
Building | Minimum
Goodwill
Percentage of fair value in excess of carrying amount (in hundredths)		10.00%
Civil
Goodwill
Gross goodwill		429,893
Accumulated impairment		(55,740)
Balance at beginning of period		374,153
Balance at end of period	374,153	374,153
Civil | Minimum
Goodwill
Percentage of fair value in excess of carrying amount (in hundredths)		10.00%
Specialty Contractors
Goodwill
Gross goodwill		141,833
Balance at beginning of period	141,833
Goodwill recorded in connection with an acquisition	1,286
Balance at end of period	143,119
Specialty Contractors | Minimum
Goodwill
Percentage of fair value in excess of carrying amount (in hundredths)		10.00%
Management Services
Goodwill
Gross goodwill		66,638
Accumulated impairment		(22,480)
Balance at beginning of period		44,158
Balance at end of period	$ 44,158	$ 44,158
Percentage of fair value in excess of carrying amount (in hundredths)		4.50%