CONDENSED 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, 2010	$ 2,178.1	$ 100.9	$ 857.5	$ 1,221.8	$ (2.1)
Comprehensive income (loss)
Net income	6.4	0	0	6.4	0
Other comprehensive income (loss), net of tax	0.2	0	0	0	0.2
Comprehensive income (loss)	6.6	0	0	6.4	0.2
Stock-based compensation	1.0	0	1.0	0	0
Balance at Mar. 31, 2011	2,185.7	100.9	858.5	1,228.2	(1.9)
Balance at Dec. 31, 2011	2,494.0	100.9	910.5	1,485.1	(2.5)
Comprehensive income (loss)
Net income	12.1	0	0	12.1	0
Other comprehensive income (loss), net of tax	0
Comprehensive income (loss)	12.1	0	0	12.1	0
Stock-based compensation	0.6	0	0.6	0	0
Balance at Mar. 31, 2012	$ 2,506.7	$ 100.9	$ 911.1	$ 1,497.2	$ (2.5)