Stockholders' Equity Tax Status of Distributions (Details) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Class of Stock [Line Items]
Document Fiscal Year Focus	2014		2013		2012
Common Stock [Member]
Class of Stock [Line Items]
Tax status of common stock dividends per share declared	0.300000		0.180000		0.180000
Series A Preferred Stock [Member]
Class of Stock [Line Items]
Tax status of preferred stock dividends per share declared	0.000000		0.968750		1.937500
Series B Preferred Stock [Member]
Class of Stock [Line Items]
Tax status of preferred stock dividends per share declared	25.776040		1.875000		1.875000
Ordinary Dividends [Member] | Common Stock [Member]
Class of Stock [Line Items]
Tax status of common stock dividends per share declared	0.281564		0.170355		0.124724
Ordinary Dividends [Member] | Series A Preferred Stock [Member]
Class of Stock [Line Items]
Tax status of preferred stock dividends per share declared	0.000000		0.966882		1.342220
Ordinary Dividends [Member] | Series B Preferred Stock [Member]
Class of Stock [Line Items]
Tax status of preferred stock dividends per share declared	0.467750		1.774673		1.298222
Long Term Capital Gain [Member] | Common Stock [Member]
Class of Stock [Line Items]
Tax status of common stock dividends per share declared	0.018436		0.009645		0.055276
Unrecaptured Section One Thousand Two Hundred Fifty Gain	0.018436	[1]	0.009457	[1]	0.055276	[1]
Cash Liquidation Distributions	0.000000		0.000000		0.000000
Long Term Capital Gain [Member] | Series A Preferred Stock [Member]
Class of Stock [Line Items]
Tax status of preferred stock dividends per share declared	0.000000		0.001868		0.595280
Unrecaptured Section One Thousand Two Hundred Fifty Gain	0.000000	[1]	0.000000	[1]	0.595280	[1]
Cash Liquidation Distributions	0.000000		25.000000		0.000000
Long Term Capital Gain [Member] | Series B Preferred Stock [Member]
Class of Stock [Line Items]
Tax status of preferred stock dividends per share declared	0.001000		0.100327		0.576078
Unrecaptured Section One Thousand Two Hundred Fifty Gain	0.001000	[1]	0.098519	[1]	0.576078	[1]
Cash Liquidation Distributions	0.253073		0.000000		0.000000

[1] (A)Represents a portion of the dividend allocated to long-term capital gain.