Unaudited Quarterly Financial Data (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Unaudited Quarterly Financial Data
Revenues	$ 1,099,291	$ 1,030,388	$ 1,053,065	$ 992,928	$ 1,114,198	$ 1,099,393	$ 985,346	$ 912,534	$ 4,175,672	$ 4,111,471	$ 3,716,317
Gross profit	139,735	120,857	105,955	100,357	126,449	115,463	87,061	86,159	466,904	415,132	395,341
Income (loss) from construction operations	70,175	58,094	39,474	36,079	60,724	54,676	(354,174)	16,963	203,822	(221,811)	168,376
Income (loss) before income taxes	53,507	37,035	25,157	23,916	48,098	44,182	(363,695)	3,573	139,615	(267,842)	137,047
Net (loss) income	33,259	23,759	15,478	14,800	41,635	42,591	(348,423)	(1,203)	87,296	(265,400)	86,148
Goodwill and intangible asset impairment							$ 376,600			$ 376,574
(Loss) earnings per share:
Basic (in dollars per share)	$ 0.69	$ 0.50	$ 0.32	$ 0.31	$ 0.88	$ 0.90	$ (7.35)	$ (0.03)	$ 1.82	$ (5.59)	$ 1.82
Diluted (in dollars per share)	$ 0.68	$ 0.49	$ 0.32	$ 0.31	$ 0.86	$ 0.88	$ (7.35)	$ (0.03)	$ 1.80	$ (5.59)	$ 1.80