Equity (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Dividends Payable [Line Items]
Common stock, dividends, per share, declared	$ 0.660	$ 0.655	$ 0.640
Common stock dividend rate percentage	100.00%	100.00%	100.00%
Preferred stock, dividends per share, declared	$ 2.000	$ 2.000	$ 1.372
Preferred stock, dividend rate, percentage	8.00%	8.00%	100.00%
Ordinary Dividend [Member]
Dividends Payable [Line Items]
Common stock, dividends, per share, declared	$ 0	$ 0.097	$ 0.018
Common stock dividend rate percentage	0.00%	14.80%	2.80%
Preferred stock, dividends per share, declared	$ 0	$ 1.565	$ 1.272
Preferred stock, dividend rate, percentage	0.00%	78.30%	92.70%
Qualified Dividend [Member]
Dividends Payable [Line Items]
Common stock, dividends, per share, declared	$ 0	$ 0.008	$ 0.001
Common stock dividend rate percentage	0.00%	1.20%	0.20%
Preferred stock, dividends per share, declared	$ 0	$ 0.128	$ 0.100
Preferred stock, dividend rate, percentage	0.00%	6.40%	7.30%
Capital Gain [Member]
Dividends Payable [Line Items]
Common stock, dividends, per share, declared	$ 0	$ 0	$ 0
Common stock dividend rate percentage	0.00%	0.00%	0.00%
Preferred stock, dividends per share, declared	$ 0	$ 0	$ 0
Preferred stock, dividend rate, percentage	0.00%	0.00%	0.00%
Unrecaptured Sec. 1250 [Member]
Dividends Payable [Line Items]
Common stock, dividends, per share, declared	$ 0	$ 0.019	$ 0
Common stock dividend rate percentage	0.00%	2.90%	0.00%
Preferred stock, dividends per share, declared	$ 0	$ 0.307	$ 0
Preferred stock, dividend rate, percentage	0.00%	15.30%	0.00%
Return of Capital [Member]
Dividends Payable [Line Items]
Common stock, dividends, per share, declared	$ 0.660	$ 0.531	$ 0.621
Common stock dividend rate percentage	100.00%	81.10%	97.00%
Preferred stock, dividends per share, declared	$ 2.000	$ 0	$ 0
Preferred stock, dividend rate, percentage	100.00%	0.00%	0.00%