Dividends (Details) (USD $)	0 Months Ended	12 Months Ended
	Oct. 31, 2013	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Common Stock [Member]
Dividends [Line Items]
Common shares, declared	$ 0.78	$ 3.020	$ 2.840	$ 2.720
Common shares, ordinary dividend		$ 2.911	$ 2.772	$ 2.349
Common shares, ordinary dividend eligible for 15% rate		$ 0.000	$ 0.000	$ 0.027
Common shares, return of capital		$ 0.000	$ 0.000	$ 0.162
Common shares, capital gain		$ 0.059	$ 0.028	$ 0.162
Common shares, paid		$ 2.970	$ 2.800	$ 2.700
Common Stock, Ordinary Dividends, Tax Rate		15.00%	15.00%	15.00%
5.417% Series 1 Cumulative Convertible Preferred [Member]
Dividends [Line Items]
5.417% Series 1 Cumulative Convertible Preferred, Declared (in dollars per share)		$ 1.354	$ 1.354	$ 1.354
Preferred Shares, percentage		5.417%	5.417%	5.417%
5.417% Series 1 Cumulative Convertible Preferred shares, ordinary dividend		$ 1.327	$ 1.340	$ 1.246
5.417% Series 1 Cumulative Convertible Preferred shares, ordinary dividend eligible for 15 % rate		$ 0.000	$ 0.000	$ 0.013
5.417% Series 1 Cumulative Convertible Preferred shares, capital gain		$ 0.027	$ 0.014	$ 0.095
5.417% Series 1 Cumulative Convertible Preferred shares, paid		$ 1.354	$ 1.354	$ 1.354
Preferred Stock, Ordinary Dividends, Tax Rate		15.00%	15.00%	15.00%