Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Additional Information (Detail)

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Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)
6 Months Ended 12 Months Ended
Jun. 30, 2015
Jun. 30, 2014
Dec. 31, 2014
Mar. 31, 2015
Mar. 31, 2014
Dec. 31, 2013
Summary Of Significant Accounting Policies [Line Items]            
Cash and cash equivalents $ 65,427,000 $ 188,948,000 $ 190,515,000 $ 135,534,000 $ 273,340,000 $ 488,777,000
Cash equivalents $ 4,700,000   $ 107,600,000      
Number of days after accounts receivable are treated as delinquent 30 days   30 days      
Number of days related to outstanding accounts receivable for analysis of the allowance for doubtful accounts            
Allowances for doubtful accounts on current receivable $ 6,032,000   $ 6,174,000      
Current retainage balances 284,300,000   307,300,000      
Non-current retainage balances 30,800,000   19,600,000      
Unbilled receivables 229,100,000   $ 163,100,000      
Decrease in fair value of reporting units considered for impairment calculation     10.00%      
Change orders and/or claims 134,700,000   $ 106,800,000      
Total amount of unrecognized tax benefits relating to uncertain tax positions 52,700,000          
Amount of unrecognized tax benefits change from year end relating to uncertain tax positions 1,800,000          
Unrecognized tax benefits increase resulting from current period tax positions 2,200,000          
Unrecognized tax benefits decrease resulting from settlements with taxing authorities 400,000          
Reasonably possible reduction to the balance of unrecognized tax benefits in succeeding 12 months upper bound 10,300,000          
General liability insurance claims deductible 10,000,000   10,000,000      
Auto liability insurance claims deductible 10,000,000   10,000,000      
Worker's compensation claims per occurrence 5,000,000   5,000,000      
Employer's liability claims subject to deductible per occurrence 1,000,000   1,000,000      
Employee health care benefit plans subject to deductible per claimant $ 375,000          
Restricted Stock Units to be Settled in Cash [Member]            
Summary Of Significant Accounting Policies [Line Items]            
Number of common stock shares that may be received by RSU holder 1          
Investments in Joint Ventures [Member]            
Summary Of Significant Accounting Policies [Line Items]            
Cash and cash equivalents $ 13,600,000   19,100,000      
Domestic Bank Accounts [Member]            
Summary Of Significant Accounting Policies [Line Items]            
Cash and cash equivalents 29,100,000   127,200,000      
Foreign Bank Accounts [Member]            
Summary Of Significant Accounting Policies [Line Items]            
Cash and cash equivalents $ 36,300,000   $ 63,300,000      
Minimum [Member]            
Summary Of Significant Accounting Policies [Line Items]            
Equity method investment ownership 20.00%          
Maximum [Member]            
Summary Of Significant Accounting Policies [Line Items]            
Equity method investment ownership 50.00%          
Percent change in contract estimates impact on operating results is less than this percentage 5.00% 5.00%