Subsequent Events Subsequent Event (Details) - USD ($)		1 Months Ended				3 Months Ended							12 Months Ended
	Mar. 30, 2016	Feb. 23, 2017	Jan. 31, 2017	Sep. 30, 2016	Nov. 30, 2015	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Subsequent Event [Line Items]
Common Stock Issued	6,037,500			3,737,500	3,737,500	19,498,000	620,828,000	485,000,000	6,037,500	608,100,000	26,200,000	342,011,000
Gains (Losses) on Extinguishment of Debt						$ (1,100,000)							$ (1,127,000)	$ (2,800,000)	$ 0
Reduction in secured borrowing balance						$ 79,100,000							$ 19,734,000	$ 26,293,000	$ 21,812,000
Weighted Average Sales Price				$ 76,810		$ 75,900	$ 76,810	$ 71,860		$ 68,000	$ 65,150	$ 63,940	$ 75,900
Net Proceeds (in Millions)						$ 1,500	$ 47,100	$ 34,400		$ 40,800	$ 1,700	$ 21,500
Subsequent Event [Member]
Subsequent Event [Line Items]
Common Stock Issued			281,000
Debt Instrument, Defeased			$ 18,900,000
Gains (Losses) on Extinguishment of Debt			$ 500,000
Reduction in secured borrowing balance		$ 10,000,000
Debt Instrument, Interest Rate, Effective Percentage		5.57%	6.49%
Weighted Average Sales Price			$ 80
Net Proceeds (in Millions)			$ 21,200,000