Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Reconciliation of the Federal income tax statutory rates to the effective rates [Abstract]
Consolidated tax provision at federal statutory rate (in hundredths)	35.00%	35.00%
State income tax provisions, net of federal income tax benefit (in hundredths)	3.60%	3.80%
All other, net (in hundredths)	(0.60%)	0.60%
Effective tax rate (in hundredths)	38.00%	39.40%
Impact of charge resulting from increases in certain state tax laws		$ 1.1
Amount of uncertain tax positions whose statute of limitations are expected to expire during the next twelve months	$ 8.4