STATEMENTS OF CHANGES IN STOCKHOLDER'S EQUITY (USD $) In Millions, unless otherwise specified	Total	Common Stock	Premium on Common Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Balance at Dec. 31, 2011	$ 2,494.0	$ 100.9	$ 910.5	$ 1,485.1	$ (2.5)
Comprehensive income (loss)
Net income	280.3	0	0	280.3	0
Other comprehensive income, net of tax	1.2	0	0	0	1.2
Dividends declared on common stock	(75.0)	0	0	(75.0)	0
Stock-based compensation	2.6	0	2.6	0	0
Balance at Dec. 31, 2012	2,703.1	100.9	913.1	1,690.4	(1.3)
Comprehensive income (loss)
Net income	292.6	0	0	292.6	0
Other comprehensive income, net of tax	1.3	0	0	0	1.3
Dividends declared on common stock	(170.0)	0	0	(170.0)	0
Stock-based compensation	2.3	0	2.3	0	0
Balance at Dec. 31, 2013	2,829.3	100.9	915.4	1,813.0	0
Comprehensive income (loss)
Net income	292.0	0	0	292.0	0
Dividends declared on common stock	(120.0)	0	0	(120.0)	0
Stock-based compensation	2.9	0	2.9	0	0
Balance at Dec. 31, 2014	$ 3,004.2	$ 100.9	$ 918.3	$ 1,985.0	$ 0