CONSOLIDATED STATEMENTS OF CAPITALIZATION - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Schedule of Capitalization, Long-term Debt [Line Items]
Common stock, par value $0.01 per share; authorized 450.0 shares; and outstanding 199.7 and 199.4 shares, respectively	$ 2.0	$ 2.0
Premium on common stock	1,099.3	1,085.6
Retained earnings	2,259.8	2,198.2
Accumulated other comprehensive loss, net of tax	(35.1)	(41.4)
Total stockholders' equity	3,326.0	3,244.4
Total long-term debt	2,755.6	2,755.3
Less long-term debt due within one year	(110.0)	0.0
Total long-term debt (excluding debt due within one year)	2,645.6	2,755.3
Total Capitalization (including long-term debt due within one year)	6,081.6	5,999.7
Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Debt Instrument, Unamortized Discount	(9.8)	(10.3)
Senior Notes [Member] | Series Due November 24, 2017 [Member] | OGE Energy [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 100.0	100.0
Debt, Weighted Average Interest Rate	0.93%
Senior Notes [Member] | Series Due January 15, 2016 [Member] | Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 110.0	110.0
Debt, Weighted Average Interest Rate	5.15%
Senior Notes [Member] | Series Due July 15, 2017 [Member] | Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 125.0	125.0
Debt, Weighted Average Interest Rate	6.50%
Senior Notes [Member] | Series Due September 1, 2018 [Member] | Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 250.0	250.0
Debt, Weighted Average Interest Rate	6.35%
Senior Notes [Member] | Series Due January 15, 2019 [Member] | Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 250.0	250.0
Debt, Weighted Average Interest Rate	8.25%
Senior Notes [Member] | Series Due July 15, 2027 [Member] | Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 125.0	125.0
Debt, Weighted Average Interest Rate	6.65%
Senior Notes [Member] | Series Due April 15, 2028 [Member] | Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 100.0	100.0
Debt, Weighted Average Interest Rate	6.50%
Senior Notes [Member] | Series Due January 15, 2036 [Member] | Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 110.0	110.0
Debt, Weighted Average Interest Rate	5.75%
Senior Notes [Member] | Series Due February 1, 2038 [Member] | Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 200.0	200.0
Debt, Weighted Average Interest Rate	6.45%
Senior Notes [Member] | Series Due June 1, 2040 [Member] | Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 250.0	250.0
Debt, Weighted Average Interest Rate	5.85%
Senior Notes [Member] | Series Due May 15, 2041 [Member] | Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 250.0	250.0
Debt, Weighted Average Interest Rate	5.25%
Senior Notes [Member] | Series Due May 1, 2043 [Member] | Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 250.0	250.0
Debt, Weighted Average Interest Rate	3.90%
Senior Notes [Member] | Series Due March 15, 2044 [Member] | Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 250.0	250.0
Debt, Weighted Average Interest Rate	4.55%
Senior Notes [Member] | Series Due December 15, 2044 [Member] | Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 250.0	250.0
Debt, Weighted Average Interest Rate	4.00%
Long-term Debt [Member] | Due August 31, 2062 [Member] | Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 10.0	10.2
Debt, Weighted Average Interest Rate	3.70%
Debentures Subject to Mandatory Redemption [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Total long-term debt	$ 135.4
Debentures Subject to Mandatory Redemption [Member] | Garfield Industrial Authority Bond [Member] | Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	47.0	47.0
Debentures Subject to Mandatory Redemption [Member] | Muskogee Industrial Authority Bond Due 2025 [Member] | Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	32.4	32.4
Debentures Subject to Mandatory Redemption [Member] | Muskogee Industrial Authority Bond Due 2027 [Member] | Og and E [Member]
Schedule of Capitalization, Long-term Debt [Line Items]
Long-term Debt, Gross	$ 56.0	$ 56.0