XML 75 R43.htm IDEA: XBRL DOCUMENT v3.20.1
Acquisitions and Impairments (Details)
$ in Millions
3 Months Ended
Mar. 31, 2020
USD ($)
Rate
MW
Mar. 31, 2019
USD ($)
Utilities Operating Expense, Operations $ 602.1 $ 666.0
Generation And Marketing [Member] | AEP Wind Holdings LLC [Member]    
Maximum Potential Amount of Future Payments Associated with Guarantee 175.0  
Guarantor Obligations, Current Carrying Value $ 33.0  
Percentage of an Asset Acquired | Rate 50.00%  
Wind Generation MWs | MW 724  
Noncash or Part Noncash Acquisition, Value of Assets Acquired $ 1,100.0  
Payments to Acquire Businesses, Gross 580.0  
Noncash or Part Noncash Acquisition, Debt Assumed 364.0  
Guarantor Obligations, Current Carrying Value, Contingent Portion 1.0  
Equity Method Investments [Member] | Generation And Marketing [Member] | AEP Wind Holdings LLC [Member]    
Acquisition 404.0  
Noncontrolling Interest [Member] | Generation And Marketing [Member] | AEP Wind Holdings LLC [Member]    
Noncash or Part Noncash Acquisition, Other Assets Acquired 135.0  
Indiana Michigan Power Co [Member]    
Cost of Purchased Power from Affiliate 36.2 59.8
Utilities Operating Expense, Operations 144.7 140.5
Ohio Power Co [Member]    
Cost of Purchased Power from Affiliate 42.4 46.1
Utilities Operating Expense, Operations 177.3 216.9
Southwestern Electric Power Co [Member]    
Utilities Operating Expense, Operations $ 92.2 $ 84.6