Business Segments, Principal Geographic Areas Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended									12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012		Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Principal Geographical Areas Information [Abstract]
Revenues										$ 4,111,471	$ 3,716,317	$ 3,199,210
Income (loss) from construction operations	60,724	54,676	(354,174)	[1]	16,963	50,792	62,036	37,035	18,513	(221,811)	168,376	172,312
Assets	3,296,410					3,613,127				3,296,410	3,613,127	2,779,220
United States
Principal Geographical Areas Information [Abstract]
Revenues										3,925,733	3,508,349	3,037,940
Income (loss) from construction operations										(195,457)	184,268	182,193
Assets	3,107,808					3,460,470				3,107,808	3,460,470	2,610,848
Foreign and U.S. Territories
Principal Geographical Areas Information [Abstract]
Revenues										185,738	207,968	161,270
Income (loss) from construction operations										18,740	28,444	23,599
Assets	188,602					152,657				188,602	152,657	168,372
Corporate [Member]
Principal Geographical Areas Information [Abstract]
Income (loss) from construction operations										$ (45,094)	$ (44,336)	$ (33,480)

[1] Includes pre-tax goodwill and intangible asset impairment of $376.6 million.