XML 47 R35.htm IDEA: XBRL DOCUMENT v3.10.0.1
Debt - Additional Information (Detail) - USD ($)
9 Months Ended
Sep. 30, 2018
Feb. 05, 2018
Dec. 31, 2017
Debt Instrument [Line Items]      
Borrowings under revolving credit agreement $ 116,400,000    
Borrowings under revolving credit agreement     $ 21,800,000
Current Revolving Credit Facility      
Debt Instrument [Line Items]      
Credit agreement, maturity date Jul. 01, 2019    
Credit agreement, maximum borrowing capacity   $ 300,000,000 600,000,000
Borrowings under revolving credit agreement $ 116,400,000    
Borrowings under revolving credit agreement     $ 21,800,000