Stockholders’ Equity (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended			2 Months Ended	3 Months Ended				9 Months Ended	12 Months Ended
	Aug. 31, 2018	Apr. 30, 2018	Mar. 31, 2018	Apr. 30, 2018	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Sep. 30, 2019	Dec. 31, 2018	Oct. 31, 2018	May 31, 2018	Oct. 31, 2017
Class of Stock [Line Items]
Shares authorized for repurchase											3,000,000
Shares repurchased					0				1,500,000
Repurchase of common stock						$ 20,172	$ 13,946	$ 27,946	$ 34,100
Shares remained available for repurchase					$ 1,000				$ 1,000
Preferred shares, par value					$ 0.0001				$ 0.0001	$ 0.0001
Common Stock A [Member]
Class of Stock [Line Items]
Authorized number of shares for issuance in offering program													2,000,000
Issuance of common stock									0
Authorized number of shares for issuance in offering program, additional shares									1,000,000
Series A Fixed-to-Floating Rate Cumulative Redeemable Perpetual Preferred Stock [Member]
Class of Stock [Line Items]
Preferred shares issued		170,900	1,600,000	170,900	2,199,610				2,199,610	2,199,610
Preferred shares dividend rate			8.50%						8.50%	8.50%
Preferred shares, par value			$ 0.0001
Preferred shares, liquidation preference			$ 25.00
Net proceeds from issuance of preferred shares		$ 4,100	$ 38,300
Payments of underwriting discount				$ 100
Series B Fixed-to-Floating Rate Cumulative Redeemable Perpetual Preferred Stock [Member]
Class of Stock [Line Items]
Preferred shares issued	1,700,000				1,955,000				1,955,000	1,955,000
Preferred shares dividend rate	8.50%								8.50%	8.50%
Preferred shares, par value	$ 0.0001
Preferred shares, liquidation preference	$ 25.00
Net proceeds from issuance of preferred shares	$ 41,200
Preferred shares issued, additional offering	255,000
Net proceeds from issuance of preferred shares, additional offering	$ 6,200
Payments of underwriting discount	$ 200
Series A Preferred Stock ATM Offering Program [Member]
Class of Stock [Line Items]
Preferred shares issued						0
Authorized number of shares for issuance in offering program												2,200,000
Authorized number of shares for issuance in offering program, additional shares									1,800,000