Business Segment Information (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Segment Reporting Information [Line Items]
Total revenue from reportable segments									$ 2,204,566,000	$ 1,960,262,000	$ 2,146,974,000
Elimination of intersegment revenue									(195,035,000)	(197,297,000)	(183,495,000)
Revenue from external customers	539,548,000	728,578,000	484,674,000	256,731,000	417,228,000	670,850,000	454,204,000	220,683,000	2,009,531,000	1,762,965,000	1,963,479,000
Gross profit	79,126,000	93,893,000	44,956,000	29,988,000	46,217,000	76,155,000	49,698,000	5,714,000	247,963,000	177,784,000	349,509,000
Depreciation, depletion and amortization									48,155,000	54,994,000	65,759,000
Segment assets	1,547,799,000				1,535,533,000				1,547,799,000	1,535,533,000	1,709,575,000
Reconciliation from Segment Totals to Consolidated [Abstract]
Gross profit (loss)	79,126,000	93,893,000	44,956,000	29,988,000	46,217,000	76,155,000	49,698,000	5,714,000	247,963,000	177,784,000	349,509,000
Selling, general and administrative expenses									162,302,000	191,593,000	228,046,000
Restructuring charges					107,300,000				2,181,000	109,279,000	9,453,000
Gain on sales of property and equipment									15,789,000	13,748,000	17,169,000
Other (expense) income, net									(9,836,000)	2,964,000	9,672,000
Income (loss) before provision for (benefit from) income taxes									89,433,000	(106,376,000)	138,851,000
Cash and cash equivalents	256,990,000				252,022,000				256,990,000	252,022,000	338,956,000	460,843,000
Short-term and long-term marketable securities	149,658,000				143,706,000				149,658,000	143,706,000
Receivables, net	251,838,000				243,986,000				251,838,000	243,986,000
Deferred income taxes	38,571,000				53,877,000				38,571,000	53,877,000
Other current assets	35,171,000				42,555,000				35,171,000	42,555,000
Property and equipment, net	447,140,000				473,607,000				447,140,000	473,607,000
Other noncurrent assets	80,616,000				82,401,000				80,616,000	82,401,000
Reportable Segment [Member]
Segment Reporting Information [Line Items]
Segment assets	649,890,000				665,303,000				649,890,000	665,303,000	767,022,000
Construction [Member]
Segment Reporting Information [Line Items]
Total revenue from reportable segments									1,043,614,000	943,245,000	1,151,743,000
Elimination of intersegment revenue									0	0	0
Revenue from external customers									1,043,614,000	943,245,000	1,151,743,000
Gross profit									124,506,000	95,709,000	209,487,000
Depreciation, depletion and amortization									14,747,000	18,148,000	25,844,000
Segment assets	111,780,000				123,153,000				111,780,000	123,153,000	156,692,000
Reconciliation from Segment Totals to Consolidated [Abstract]
Gross profit (loss)									124,506,000	95,709,000	209,487,000
Construction [Member] | Maximum [Member]
Segment Reporting Information [Line Items]
Typical Contract Value									75,000,000
Large Project Construction [Member]
Segment Reporting Information [Line Items]
Total revenue from reportable segments									725,043,000	584,406,000	603,517,000
Elimination of intersegment revenue									0	0	0
Revenue from external customers									725,043,000	584,406,000	603,517,000
Gross profit									104,108,000	67,307,000	120,100,000
Depreciation, depletion and amortization									4,547,000	2,759,000	5,311,000
Segment assets	110,441,000				80,259,000				110,441,000	80,259,000	78,563,000
Reconciliation from Segment Totals to Consolidated [Abstract]
Gross profit (loss)									104,108,000	67,307,000	120,100,000
Large Project Construction [Member] | Minimum [Member]
Segment Reporting Information [Line Items]
Typical Contract Value									75,000,000
Construction Materials [Member]
Segment Reporting Information [Line Items]
Total revenue from reportable segments									415,618,000	419,355,000	389,440,000
Elimination of intersegment revenue									(195,035,000)	(197,297,000)	(183,495,000)
Revenue from external customers									220,583,000	222,058,000	205,945,000
Gross profit									16,641,000	12,018,000	21,240,000
Depreciation, depletion and amortization									28,672,000	33,565,000	34,047,000
Segment assets	352,619,000				374,205,000				352,619,000	374,205,000	377,352,000
Reconciliation from Segment Totals to Consolidated [Abstract]
Gross profit (loss)									16,641,000	12,018,000	21,240,000
Real Estate Segment [Member]
Segment Reporting Information [Line Items]
Total revenue from reportable segments									20,291,000	13,256,000	2,274,000
Elimination of intersegment revenue									0	0	0
Revenue from external customers									20,291,000	13,256,000	2,274,000
Gross profit									2,708,000	2,750,000	(1,318,000)
Depreciation, depletion and amortization									189,000	522,000	557,000
Segment assets	75,050,000				87,686,000				75,050,000	87,686,000	154,415,000
Reconciliation from Segment Totals to Consolidated [Abstract]
Gross profit (loss)									2,708,000	2,750,000	(1,318,000)
Unallocated Amount to Segment [Member]
Reconciliation from Segment Totals to Consolidated [Abstract]
Cash and cash equivalents	256,990,000				252,022,000				256,990,000	252,022,000	338,956,000
Short-term and long-term marketable securities	149,658,000				143,706,000				149,658,000	143,706,000	119,385,000
Receivables, net	251,838,000				243,986,000				251,838,000	243,986,000	280,252,000
Deferred income taxes	38,571,000				53,877,000				38,571,000	53,877,000	31,034,000
Other current assets	76,074,000				55,970,000				76,074,000	55,970,000	63,814,000
Property and equipment, net	46,180,000				42,874,000				46,180,000	42,874,000	45,503,000
Other noncurrent assets	$ 78,598,000				$ 77,795,000				$ 78,598,000	$ 77,795,000	$ 63,609,000