XML 79 R109.htm IDEA: XBRL DOCUMENT v3.20.1
Financial Assets and Financial Liabilities - Additional Information (Detail) - USD ($)
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Disclosure Of Financial Instruments [Line Items]      
Dividends received $ 109,000 $ 105,000 $ 100,000
Maximum borrowing capacity 287,017,000 $ 275,334,000  
Unused portion of the credit lines $ 208,000,000    
Liquidity discount 30.00% 30.00%  
Line Of Credit 1 [Member]      
Disclosure Of Financial Instruments [Line Items]      
Unused portion of the credit lines $ 207,928,000 $ 182,361,000  
Letters of Credit [Member]      
Disclosure Of Financial Instruments [Line Items]      
Unused portion of the credit lines 113,255,000 92,256,000  
Open letters of credit [Member]      
Disclosure Of Financial Instruments [Line Items]      
Unused portion of the credit lines 15,209,000 22,426,000  
Foreign currency forward contracts [Member]      
Disclosure Of Financial Instruments [Line Items]      
Outstanding forward contracts, notional amount $ (900,000) $ (9,400,000)