Earnings Per Share (Narrative) (Details) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Earnings Per Share Narrative [Line Items]
Weighted average unvested shares outstanding	0.3	0.3
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0	0
5.417% Series 1 Cumulative Convertible Preferred [Member]
Earnings Per Share Narrative [Line Items]
Preferred Stock, Dividend Rate, Percentage	5.417%	5.417%	5.417%