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Long-Term Debt - Additional information (Detail) - USD ($)
1 Months Ended 12 Months Ended
Sep. 11, 2017
Oct. 31, 2017
Dec. 31, 2016
Oct. 31, 2015
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Debt Instrument [Line Items]              
Purchase price, net of cash acquired         $ 59,798,000 $ 0 $ 0
Interest rate cap premiums              
Debt Instrument [Line Items]              
Hedging asset       $ 135,000,000      
Payments for hedging asset       $ 1,000,000      
New Credit Facilities | First Two Years              
Debt Instrument [Line Items]              
Prepayment percentage of principal         5.00%    
New Credit Facilities | Third Year              
Debt Instrument [Line Items]              
Prepayment percentage of principal         7.50%    
New Credit Facilities | Fourth and Fifth Year              
Debt Instrument [Line Items]              
Prepayment percentage of principal         10.00%    
New Credit Facilities | Federal Funds Rate              
Debt Instrument [Line Items]              
Fixed rate spread (percent)         0.50%    
New Credit Facilities | Eurodollar Rate              
Debt Instrument [Line Items]              
Fixed rate spread (percent)         1.00%    
New Credit Facilities | Minimum              
Debt Instrument [Line Items]              
Commitment fee (percent)         0.175%    
New Credit Facilities | Minimum | LIBOR Rate              
Debt Instrument [Line Items]              
Variable rate spread (percent)         1.50%    
New Credit Facilities | Minimum | Base Rate              
Debt Instrument [Line Items]              
Variable rate spread (percent)         0.50%    
New Credit Facilities | Maximum              
Debt Instrument [Line Items]              
Commitment fee (percent)         0.30%    
New Credit Facilities | Maximum | LIBOR Rate              
Debt Instrument [Line Items]              
Variable rate spread (percent)         2.75%    
New Credit Facilities | Maximum | Base Rate              
Debt Instrument [Line Items]              
Variable rate spread (percent)         1.75%    
New Credit Facilities | Term Loan              
Debt Instrument [Line Items]              
Face amount of instrument         $ 275,000,000.0    
Term of debt instrument         5 years    
Repayments of line of credit         $ 10,000,000    
New Credit Facilities | Revolving Credit Facility              
Debt Instrument [Line Items]              
Face amount of instrument         200,000,000.0    
Debt issuance costs         4,800,000    
Remaining borrowing capacity         141,600,000    
Proceeds from line of credit         58,100,000    
Outstanding standby letters of credit         300,000    
Parsons, KS | Municipal Bonds              
Debt Instrument [Line Items]              
Purchase of industrial revenue bonds     $ 9,900,000   14,200,000 9,900,000  
Parsons, KS              
Debt Instrument [Line Items]              
Proceeds received from sale of property to be leased back     9,900,000   14,200,000    
Total lease liability from assets sold     $ 9,900,000   $ 14,200,000 $ 9,900,000  
Lightning Diversion Systems, Inc.              
Debt Instrument [Line Items]              
Purchase price, net of cash acquired $ 60,000,000            
Payments to acquire business $ 61,400,000 $ 600,000