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Debt - $500 Million Term Loan B - Additional Information (Detail) - USD ($)
1 Months Ended 12 Months Ended
May 31, 2017
Dec. 31, 2017
May 10, 2017
Debt Instrument [Line Items]      
Net proceeds from credit facility   $ 500,000,000  
$400 Million Term Loan Facility [Member]      
Debt Instrument [Line Items]      
Total credit facility     $ 400,000,000
$500 Million Term Loan B [Member]      
Debt Instrument [Line Items]      
Total credit facility   $ 500,000,000  
Maturity date for credit facility   May 11, 2024  
Debt Instrument, description of interest rate   (i) LIBOR plus 2.25% or (ii) a base rate as set in the Amended Credit Agreement.  
Spread rate added to LIBOR   2.25%  
Net proceeds from credit facility $ 114,300,000    
Periodic payment, percentage on principal amount   1.00%