Common and Preferred Stock (Assumptions) (Details) (Options [Member])	12 Months Ended
	Dec. 31, 2011 Years		Dec. 31, 2010 Years		Dec. 31, 2009 Years
Options [Member]
Assumptions used to estimate the fair value of options using the Black-Scholes option pricing model [Abstract]
Expected volatility (in hundredths)	21.54%	[1]
Expected volatility, low range (in hundredths)			20.74%	[1]	19.02%	[1]
Expected volatility, high range (in hundredths)			21.64%	[1]	20.23%	[1]
Expected dividends (in hundredths)	4.03%
Expected dividends, low range (in hundredths)			3.61%		3.35%
Expected dividends, high range (in hundredths)			4.39%		3.71%
Expected term (years)	6	[2]	6	[2]	6	[2]
Risk-free rate (in hundredths)	2.80%
Risk-free rate, low range (in hundredths)			1.65%		2.68%
Risk-free rate, high range (in hundredths)			2.91%		2.97%

[1] Based on historical experience.

[2] Based on historical exercise and post-vesting cancellation experience adjusted for outstanding awards.