INCOME TAXES - COMPONENTS OF TAX EXPENSE (DETAILS) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Current tax expense (benefit):
Federal	$ 0	$ 7.4	$ (3.4)
State	3.5	2.7	(1.3)
Total current	3.5	10.1	(4.7)
Deferred tax expense:
Federal	134.9	131.5	76.7
State	10.8	13.2	9.3
Total deferred	145.7	144.7	86.0
Total tax expense related to income	$ 149.2	$ 154.8	$ 81.3