Equity - Common Stock (Details) - USD ($) $ in Millions		6 Months Ended
	May. 19, 2015	Jun. 30, 2015	Jun. 30, 2014
Subsidiary, Sale of Stock [Line Items]
Proceeds from issuance of common stock		$ 215.0	$ 190.7
Cumulative Preferred Stock Subject to Mandatory Redemption [Member]
Subsidiary, Sale of Stock [Line Items]
Conversion of preferred stock to common stock (in shares)		(100,000)
Cumulative Preferred Stock Subject to Mandatory Redemption [Member] | Series A Preferred Stock [Member]
Subsidiary, Sale of Stock [Line Items]
Preferred stock outstanding (in shares)	100,000	100,000	100,000
Common Stock [Member]
Subsidiary, Sale of Stock [Line Items]
Issuance of common stock (in shares)		8,625,000
Proceeds from issuance of common stock		$ 215.3
Payments of Stock Issuance Costs		$ 0.3
Conversion of preferred stock to common stock (in shares)	8,554,948	8,554,948