XML 146 R129.htm IDEA: XBRL DOCUMENT v3.10.0.1
Schedule of Fair Value Other Financial Instruments Measured (Detail) - Fair Value, Measurements, Recurring - USD ($)
$ in Thousands
Dec. 31, 2018
Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair value of assets $ 327,542 $ 399,322
Quoted Prices In Active Markets (Level 1)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair value of assets 327,542 399,322
Money Market Cash Equivalents    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair value of assets 327,542 399,322
Money Market Cash Equivalents | Quoted Prices In Active Markets (Level 1)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Fair value of assets $ 327,542 $ 399,322