Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Additional Information (Details)

v3.20.4
Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)
 3 Months Ended 6 Months Ended
Oct. 29, 2020
Oct. 01, 2020
Sep. 03, 2020
Sep. 19, 2019
Dec. 31, 2020
Sep. 30, 2020
Dec. 31, 2019
Dec. 31, 2020
Dec. 31, 2019
Jun. 30, 2020
Summary Of Significant Accounting Policies [Line Items]                    
Restricted cash         $ 200,000     $ 200,000   $ 200,000
Notice period to terminate contract               14 days    
Precious metals held under financing arrangements [1]         $ 160,255,000     $ 160,255,000   178,577,000
Operating lease payments               $ 800,000 $ 700,000  
Operating lease term (in years)         4 years 2 months 12 days     4 years 2 months 12 days    
Operating lease (percent)         4.90%     4.90%    
Percentage of investments in privately-held entities accounted under equity method       31.20%            
Metals purchase by customer maximum specified time period               1 year    
Metal delivers to customer after receiving customers deposit based on prevailing current spot price percentage               110.00%    
Unpriced metal is subject to margin call If deposit falls below percentage of value of unpriced metal               105.00%    
Percentage to remit partial payment of total order price               20.00%    
Advertising expense         $ 622,000   $ 346,000 $ 1,322,000 809,000  
Cost of sales         $ 1,499,993,000   1,047,459,000 3,329,964,000 2,520,133,000  
Dividends declared, date Oct. 29, 2020   Sep. 03, 2020              
Dividends declared, per common share $ 1.50   $ 1.50   $ 1.50 $ 1.50        
Dividends payable, date of record Nov. 23, 2020   Sep. 21, 2020              
Dividends paid               $ 21,200,000    
Change in accounting principle, accounting standards update, adopted         true     true    
Change in accounting principle, accounting standards update, immaterial effect         true     true    
Accounting standards update [Extensible List]               us-gaap:AccountingStandardsUpdate201815Member    
Shipping and Handling                    
Summary Of Significant Accounting Policies [Line Items]                    
Cost of sales         $ 1,800,000   $ 1,400,000 $ 5,000,000 $ 2,800,000  
Convertible Revolving Credit Facility                    
Summary Of Significant Accounting Policies [Line Items]                    
Line of credit facility, maximum borrowing capacity       $ 4,000,000            
Line of credit facility, interest rate       12.00%            
Line of credit facility, expiration date       Sep. 18, 2022            
Line of credit facility, percentage of outstanding principal converted into borrower's issued and outstanding common stock       22.00%            
Line of credit facility, percentage of repay outstanding unrelated third-party debt in exchange for borrower's issued and outstanding common stock       27.50%            
Line of credit facility, additional interest rate in case of default by borrower       10.00%            
Line of credit facility, entitlement of interest to lender in event of excess gross sales price       $ 9,900,000            
Line of credit facility, conversion amount   $ 1,000,000                
Line of credit facility, outstanding balance   3,500,000     $ 2,500,000     $ 2,500,000   $ 3,500,000
Line of credit facility, repayment of third-party loan   $ 5,800,000                
Minimum                    
Summary Of Significant Accounting Policies [Line Items]                    
Estimated useful lives of related assets               3 years    
Estimated useful lives of intangibles               3 years    
Percentage of investments in privately-held entities accounted under equity method         20.00%     20.00%    
Maximum                    
Summary Of Significant Accounting Policies [Line Items]                    
Estimated useful lives of related assets               25 years    
Estimated useful lives of intangibles               15 years    
Percentage of investments in privately-held entities accounted under equity method         50.00%     50.00%    
Customer locks period for purchase price               2 years    
[1] Includes amounts of the consolidated variable interest entity, which is presented separately in the table below.