Quarterly report pursuant to Section 13 or 15(d)

Related Party Transactions (Details)

v3.20.2
Related Party Transactions (Details) - NSP China - Subsidiaries - USD ($)
3 Months Ended 9 Months Ended
Sep. 30, 2020
Sep. 30, 2019
Sep. 30, 2020
Sep. 30, 2019
Dec. 31, 2019
Related Party Transaction [Line Items]          
Notes receivable, related parties, current $ 5,200,000   $ 5,200,000   $ 6,100,000
Company's Joint Venture Partner          
Related Party Transaction [Line Items]          
Notes receivable, related parties, current 1,300,000   1,300,000   $ 1,500,000
Notes Receivable          
Related Party Transaction [Line Items]          
Related party transaction, amount $ 0   $ 0    
Related party transaction, rate     3.00%    
Notes Receivable | Company's Joint Venture Partner          
Related Party Transaction [Line Items]          
Related party transaction, amount   $ 0   $ 0