XML 91 R58.htm IDEA: XBRL DOCUMENT v3.20.1
Income Taxes Income Taxes (Schedule of Effective Income Tax Rate Reconciliation) (Details)
3 Months Ended
Mar. 31, 2020
Mar. 31, 2019
Income Taxes [Line Items]    
Federal statutory corporate income tax rate 21.00% 21.00%
Amortization of excess deferred taxes (9.00%) (7.00%)
Depreciation differences (1.00%) 0.00%
Amortization of deferred investment tax credit 0.00% (1.00%)
State tax 6.00% 6.00%
Stock-based compensation (5.00%) (7.00%)
Other permanent items 0.00% 0.00%
Effective income tax rate 12.00% 12.00%
Union Electric Company    
Income Taxes [Line Items]    
Federal statutory corporate income tax rate 21.00% 21.00%
Amortization of excess deferred taxes (15.00%) (12.00%)
Depreciation differences 0.00% 0.00%
Amortization of deferred investment tax credit (1.00%) (1.00%)
State tax 3.00% 4.00%
Stock-based compensation 0.00% 0.00%
Other permanent items 0.00% (3.00%)
Effective income tax rate 8.00% 9.00%
Ameren Illinois Company    
Income Taxes [Line Items]    
Federal statutory corporate income tax rate 21.00% 21.00%
Amortization of excess deferred taxes (3.00%) (3.00%)
Depreciation differences (1.00%) 0.00%
Amortization of deferred investment tax credit 0.00% 0.00%
State tax 7.00% 7.00%
Stock-based compensation 0.00% 0.00%
Other permanent items 0.00% 0.00%
Effective income tax rate 24.00% 25.00%