Stockholders' Equity (Details) (USD $)	1 Months Ended	3 Months Ended	12 Months Ended
	May 31, 2013	Jun. 30, 2014	Dec. 31, 2014 Rate	Dec. 31, 2013	Dec. 31, 2012	Apr. 14, 2014	May 13, 2013
Class of Stock [Line Items]
Common Stock, Shares, Issued during a Period			26,700,000	85,600,000
Preferred Stock, Shares Outstanding			0	3,791,000
Preferred Stock, Dividend Rate, Percentage			7.50%	7.50%
Preferred Stock, Liquidation Preference Per Share			$ 25	$ 25
Common Stock, Shares, Issued			220,078,986	193,236,454
Proceeds from Issuance of Common Stock			$ 321,900,000	$ 826,200,000
Preferred Stock, Par or Stated Value Per Share			$ 1	$ 1		$ 1.00	$ 1.00
Preferred Stock, Redemption Price Per Share						$ 25.00	$ 25.00
Preferred Stock, Redemption Amount						94,800,000	74,800,000
Preferred Share Original Issuance Costs		(3,500,000)	3,530,000	2,656,000
Preferred Stock, Redemption Amount, Reduction of Net Loss	$ 2,700,000
Percentage of Restrictions on Ownership of Company Common and Preferred Stock			3.90%
Document Fiscal Year Focus			2014	2013	2012