Stockholders' Equity Tax Status of Distributions (Details) - USD ($)		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Class of Stock [Line Items]
Document Fiscal Year Focus		2015	2014	2013
Common Stock [Member]
Class of Stock [Line Items]
Tax status of common stock dividends per share declared		$ 0.320000	$ 0.300000	$ 0.180000
Series A Preferred Stock [Member]
Class of Stock [Line Items]
Tax status of preferred stock dividends per share declared				25.968750
Series B Preferred Stock [Member]
Class of Stock [Line Items]
Tax status of preferred stock dividends per share declared			25.776040	1.875000
Ordinary Dividends [Member] | Common Stock [Member]
Class of Stock [Line Items]
Tax status of common stock dividends per share declared		0.161738	0.281564	0.170355
Ordinary Dividends [Member] | Series A Preferred Stock [Member]
Class of Stock [Line Items]
Tax status of preferred stock dividends per share declared				0.966882
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
Long Term Capital Gain [Member] | Common Stock [Member]
Class of Stock [Line Items]
Tax status of common stock dividends per share declared		0.158262	0.018436	0.009645
Unrecaptured Section One Thousand Two Hundred Fifty Gain	[1]	$ 0.097271	$ 0.018436	$ 0.009457
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				$ 0.001868
Unrecaptured Section One Thousand Two Hundred Fifty Gain	[1]			$ 0.000000
Cash Liquidation Distributions				$ 25.000000
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
Unrecaptured Section One Thousand Two Hundred Fifty Gain	[1]		$ 0.001000	$ 0.098519
Cash Liquidation Distributions			$ 25.307290	$ 0.000000

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