XML 54 R43.htm IDEA: XBRL DOCUMENT v3.10.0.1
Investments - Additional Information (Detail) - USD ($)
$ in Thousands
9 Months Ended
Sep. 30, 2018
Sep. 30, 2017
Dec. 31, 2017
Schedule of Held-to-maturity Securities [Line Items]      
Cash and cash equivalents $ 117,700   $ 55,600
Proceeds received in connection with term loan amendment 100,000 $ 300,000  
Held-to-Maturity Securities [Member]      
Schedule of Held-to-maturity Securities [Line Items]      
Investments $ 15,400   $ 30,100