Fair Value Disclosures (Narrative) (Details) (USD $) In Millions, unless otherwise specified		12 Months Ended						1 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2012 Government [Member]	Dec. 31, 2011 Government [Member]	Dec. 31, 2010 Government [Member]	Dec. 31, 2012 Corporate/Other Bonds [Member]	Dec. 31, 2011 Corporate/Other Bonds [Member]	Dec. 31, 2010 Corporate/Other Bonds [Member]	Apr. 30, 2011 Lake Erie Land [Member]	Dec. 31, 2012 Lake Erie Land [Member]
Fair Value Disclosure [Line Items]
Impaired Assets to be Disposed of by Method Other than Sale, Amount of Impairment Loss								$ 14.7	$ 0
Net realized gain on available for sale debt securities		0.6	0.5	0.7	0.3	0.9	1.0
Available-for-sale securities, maturities of less than a year	$ 2.1