XML 43 R31.htm IDEA: XBRL DOCUMENT v3.21.1
Fair Value Measurements (Tables)
 3 Months Ended
Mar. 31, 2021
Fair Value Disclosures [Abstract]  
Schedule of Fair Value and Carrying Amount of PRM Financial Instruments [Table Text Block] The following table presents the carrying amount and fair value of the Registrants' financial instruments at March 31, 2021 and December 31, 2020, as well as the classification level within the fair value hierarchy.
March 31,December 31,
 20212020
(In millions)Carrying Amount Fair
Value		Carrying Amount  Fair
Value		Classification
Long-term Debt (including Long-term Debt due within one year):    
OG&E Senior Notes$3,350.2 $3,831.0 $3,349.6 $4,182.1 Level 2
OG&E Industrial Authority Bonds$135.4 $135.4 $135.4 $135.4 Level 2
Tinker Debt$9.4 $9.9 $9.4 $10.7 Level 3