Business Segments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Reportable segment information
Revenues	$ 1,084,510	$ 1,053,065	$ 2,039,743	$ 2,045,993
Income from construction operations:
Income from construction operations	65,443	39,474	106,940	75,553
Total	3,654,523		3,654,523		3,397,438
Corporate
Income from construction operations:
Income from construction operations	(12,866)	(10,846)	(25,354)	(22,650)
Total	700,356		700,356		615,108
Operating segment
Reportable segment information
Revenues	1,110,435	1,084,369	2,090,287	2,142,704
Income from construction operations:
Income from construction operations	78,309	50,320	132,294	98,203
Total	2,954,167		2,954,167		2,782,330
Intersegment elimination
Reportable segment information
Revenues	(25,925)	(31,304)	(50,544)	(96,711)
Civil
Reportable segment information
Revenues	390,539	346,196	755,695	600,157
Civil | Operating segment
Reportable segment information
Revenues	398,123	356,711	774,515	661,960
Income from construction operations:
Income from construction operations	58,002	31,674	102,347	54,924
Total	1,499,197		1,499,197		1,384,937
Civil | Intersegment elimination
Reportable segment information
Revenues	(7,584)	(10,515)	(18,820)	(61,803)
Building
Reportable segment information
Revenues	372,012	422,833	669,944	859,933
Building | Operating segment
Reportable segment information
Revenues	390,353	443,622	701,668	894,831
Income from construction operations:
Income from construction operations	7,674	2,661	9,497	8,008
Total	702,164		702,164		663,314
Building | Intersegment elimination
Reportable segment information
Revenues	(18,341)	(20,789)	(31,724)	(34,898)
Specialty Contractors
Reportable segment information
Revenues	321,959	284,036	614,104	585,903
Specialty Contractors | Operating segment
Reportable segment information
Revenues	321,959	284,036	614,104	585,913
Income from construction operations:
Income from construction operations	12,633	15,985	20,450	35,271
Total	752,806		752,806		734,079
Specialty Contractors | Intersegment elimination
Reportable segment information
Revenues				$ (10)