Employee Benefit Plans (Details)	12 Months Ended
	Dec. 31, 2015 USD ($) participant	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Employee Benefits Plans [Line Items]
Defined Contribution Plan, Maximum Annual Contribution Per Employee, Percent	50.00%
Defined Contribution Plan, Maximum Annual Contribution Per Employee, Dollar Amount	$ 18,000
Defined Contribution Plan, Employer Matching Contribution, Percent	6.00%
Defined Contribution Plan, Cost Recognized	$ 5,400,000	$ 5,000,000	$ 4,100,000
Defined Contribution Plan, Employer Discretionary Contribution Amount			100,000
Number of Participants in Non Qualifed Deferred Compensation Plan | participant	52
Deferred Compensation Liability, Current and Noncurrent	$ 19,700,000	21,700,000
Multiemployer Plan, Period Contributions	$ 28,559,000	29,422,000	27,165,000
Multiemployer Plans, Maximum Percent Funded Status for Red Zone	65.00%
Multiemployer Plans, Maximum Percent Funded Status for Yellow Zone and Minmum Percent for Green Zone	80.00%
Locals 302 and 612 Operating Engineers Employers Retirement Fund [Member]
Employee Benefits Plans [Line Items]
Multiemployer Plan, Period Contributions	$ 3,000,000	3,043,000	3,260,000
Operating Engineers Pension Trust Fund [Member]
Employee Benefits Plans [Line Items]
Multiemployer Plan, Period Contributions	3,647,000	3,001,000	2,768,000
Pension Trust Fund for Operating Engineers Pension Plan [Member]
Employee Benefits Plans [Line Items]
Multiemployer Plan, Period Contributions	9,070,000	9,590,000	8,193,000
Laborers Pension Trust Fund for Northern California [Member] [Member]
Employee Benefits Plans [Line Items]
Multiemployer Plan, Period Contributions	2,403,000	2,682,000	2,500,000
Laborers Pension Fund [Member]
Employee Benefits Plans [Line Items]
Multiemployer Plan, Period Contributions	1,919,000	2,230,000	1,608,000
All Other Pension Trust Funds [Member]
Employee Benefits Plans [Line Items]
Multiemployer Plan, Period Contributions	$ 8,520,000	$ 8,876,000	$ 8,836,000