XML 55 R50.htm IDEA: XBRL DOCUMENT v3.19.3
Income Taxes Additional Information (Details)
3 Months Ended 9 Months Ended
Sep. 30, 2019
USD ($)
Mar. 31, 2019
USD ($)
Investment
Sep. 30, 2018
USD ($)
Sep. 30, 2019
USD ($)
Sep. 30, 2018
USD ($)
Dec. 31, 2018
USD ($)
Income Taxes [Line Items]            
Document Period End Date       Sep. 30, 2019    
Valuation allowance $ 0   $ 0 $ 0 $ 0 $ 0
Effective Income Tax Rate Reconciliation, Percent 16.50%   17.70% 24.00% 19.20%  
Alternative Energy            
Income Taxes [Line Items]            
Effective Income Tax Rate Reconciliation, Tax Credit, Investment, Amount   $ 156,100,000        
Number of Sponsors | Investment   3