Subsequent Events Subsequent Events (Details) - USD ($)			1 Months Ended																										3 Months Ended								12 Months Ended
	Mar. 16, 2020	Mar. 14, 2020	Feb. 29, 2020	Jan. 31, 2020	Dec. 31, 2019		Nov. 30, 2019	[1]	Oct. 31, 2019	[1]	Sep. 30, 2019	[1]	Aug. 31, 2019	[1]	Jul. 31, 2019	[1]	Jun. 30, 2019	[1]	May 31, 2019	[1]	Apr. 30, 2019	[1]	Mar. 31, 2019	[1]	Feb. 28, 2019	[1]	Jan. 31, 2019	[1]	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Feb. 21, 2020
Subsequent Event [Line Items]
Dividends declared per common share, subsequent period					$ 0.15	[1]	$ 0.15		$ 0.15		$ 0.15		$ 0.15		$ 0.18		$ 0.18		$ 0.18		$ 0.18		$ 0.18		$ 0.18		$ 0.18		$ 0.45	$ 0.48	$ 0.54	$ 0.54	$ 0.54	$ 0.54	$ 0.54	$ 0.54
Preferred Stock, Par or Stated Value Per Share					0.01																								0.01								$ 0.01
Preferred Stock, Liquidation Preference Per Share					$ 25.00																								$ 25.00								$ 25.00
Stock Issued During Period, Value, New Issues																																					$ 83,812,000	$ 43,457,000	$ 78,532,000
Series A Preferred Stock [Member]
Subsequent Event [Line Items]
Preferred Stock, Dividend Rate, Percentage																																					8.50%
Series B Preferred Stock [Member]
Subsequent Event [Line Items]
Preferred Stock, Dividend Rate, Percentage																																					7.625%
Subsequent Event [Member]
Subsequent Event [Line Items]
Dividends declared per common share, subsequent period			$ 0.15	$ 0.15
Dividends Payable, Date to be Paid			Mar. 02, 2020	Feb. 03, 2020
Dividends Payable, Date of Record			Feb. 24, 2020	Jan. 21, 2020
Preferred Stock, Liquidation Preference Per Share		$ 25.00
Subsequent Event [Member] | Series A Preferred Stock [Member]
Subsequent Event [Line Items]
Preferred Stock, Redemption Date		Mar. 14, 2020
Stock Redeemed or Called During Period, Shares		2,300,000
Subsequent Event [Member] | Series B Preferred Stock [Member]
Subsequent Event [Line Items]
Preferred Stock, Redemption Date	Mar. 16, 2020
Stock Redeemed or Called During Period, Shares	1,700,000
Subsequent Event [Member] | Series C Preferred Stock
Subsequent Event [Line Items]
Stock Issued During Period, Shares, New Issues			4,460,000
Preferred Stock, Dividend Rate, Percentage			6.90%
Preferred Stock, Par or Stated Value Per Share																																								$ 0.01
Preferred Stock, Liquidation Preference Per Share																																								$ 25.00
Stock Issued During Period, Value, New Issues			$ 107,988,000

[1] Amounts declared have been adjusted to reflect the effect of the 1-for-3 reverse stock split.