• Filing Date: 2018-03-07
  • Form Type: 10-K
  • Description: Annual report
v3.8.0.1
Long-Term Debt (3.75% Promissory Note) - Additional Information (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Aug. 16, 2016
Debt Instrument [Line Items]      
Proceeds from the issuance of long-term debt $ 143,859 $ 18,200  
3.75% Promissory Note [Member]      
Debt Instrument [Line Items]      
Secured loan agreement period 20 years    
Proceeds from the issuance of long-term debt $ 9,000    
Fixed annual interest rate 3.75%   3.75%
Debt instrument, payment frequency description 240 monthly    
Debt instrument periodic payment $ 53    
Debt instruments, payment terms description The promissory note may be repaid in full after September 1, 2017 as long as the Company provides at least 60 days' written notice and pays a prepayment premium as specified in the loan agreement. In addition, the lender may require full payment of the outstanding principal and unpaid interest on September 1, 2031 provided a written notice of its intention to call the note is given at least six months in advance.    
Outstanding principal and interest payment due date Sep. 01, 2031