CONDENSED STATEMENTS OF CHANGES IN STOCKHOLDER'S EQUITY (Unaudited) - USD ($) $ in Millions	Total	Common Stock	Premium on Common Stock	Retained Earnings
Balance at Dec. 31, 2015	$ 3,155.7	$ 100.9	$ 920.9	$ 2,133.9
Changes in Stockholders' Equity
Net income	6.1	0.0	0.0	6.1
Dividends declared on common stock	(30.0)	0.0	0.0	(30.0)
Stock-based compensation	0.8	0.0	0.8	0.0
Balance at Mar. 31, 2016	3,132.6	100.9	921.7	2,110.0
Balance at Dec. 31, 2016	3,252.1	100.9	923.2	2,228.0
Changes in Stockholders' Equity
Net income	16.2	0.0	0.0	16.2
Dividends declared on common stock	0.0	0.0	0.0	0.0
Stock-based compensation	0.8	0.0	0.8	0.0
Balance at Mar. 31, 2017	$ 3,269.1	$ 100.9	$ 924.0	$ 2,244.2