Unaudited Quarterly Financial Data (Details) (USD $) In Thousands, except Per Share data, 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
Unaudited Quarterly Financial Data [Abstract]
Revenues	$ 1,114,198	$ 1,099,393	$ 985,346		$ 912,534	$ 1,114,760	$ 1,166,410	$ 819,858	$ 615,289	$ 4,111,471	$ 3,716,317	$ 3,199,210
Gross profit	126,449	115,463	87,061		86,159	125,313	120,355	87,210	62,463	415,132	395,341	337,848
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
Income (loss) before income taxes	48,098	44,182	(363,695)		3,573	38,788	56,333	31,015	10,911	(267,842)	137,047	159,468
Net (loss) income	41,635	42,591	(348,423)		(1,203)	24,048	35,477	19,694	6,929	(265,400)	86,148	103,500
Earnings per share [Abstract]
Basic (in dollars per share)	$ 0.88	$ 0.90	$ (7.35)	[1]	$ (0.03)	$ 0.51	$ 0.75	$ 0.42	$ 0.15	$ (5.59)	$ 1.82	$ 2.15
Diluted (in dollars per share)	$ 0.86	$ 0.88	$ (7.35)		$ (0.03)	$ 0.50	$ 0.74	$ 0.41	$ 0.14	$ (5.59)	$ 1.80	$ 2.13
Goodwill and intangible assets impairment			$ 376,574							$ 376,574	$ 0	$ 0

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