CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
CONSOLIDATED STATEMENTS OF OPERATIONS [Abstract]
REVENUE	$ 1,200,830	$ 1,340,739	$ 1,312,438	$ 1,066,465	$ 1,201,877	$ 1,250,689	$ 1,084,510	$ 955,233	$ 4,920,472	$ 4,492,309	$ 4,175,672
COST OF OPERATIONS									(4,564,219)	(3,986,867)	(3,708,768)
GROSS PROFIT	66,673	100,201	98,620	90,759	129,723	140,841	129,531	105,347	356,253	505,442	466,904
General and administrative expenses									(250,840)	(263,752)	(263,082)
INCOME FROM CONSTRUCTION OPERATIONS	15,474	38,974	30,881	20,084	64,396	70,354	65,443	41,497	105,413	241,690	203,822
Other income (expense), net									12,453	(9,536)	(18,575)
Interest expense									(44,027)	(44,716)	(45,632)
INCOME BEFORE INCOME TAXES	11,687	33,955	19,992	8,205	53,917	58,616	47,612	27,293	73,839	187,438	139,615
Provision for income taxes									(28,547)	(79,502)	(52,319)
NET INCOME	$ 8,712	$ 19,677	$ 11,777	$ 5,126	$ 27,722	$ 35,730	$ 28,545	$ 15,939	$ 45,292	$ 107,936	$ 87,296
BASIC EARNINGS PER COMMON SHARE	$ 0.18	$ 0.40	$ 0.24	$ 0.11	$ 0.57	$ 0.74	$ 0.59	$ 0.33	$ 0.92	$ 2.22	$ 1.82
DILUTED EARNINGS PER COMMON SHARE	$ 0.18	$ 0.40	$ 0.24	$ 0.10	$ 0.56	$ 0.73	$ 0.58	$ 0.33	$ 0.91	$ 2.20	$ 1.80
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING:
BASIC									48,981	48,562	47,851
DILUTED									49,666	49,114	48,589