TWO Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity Preferred Stock Issuances (Details)

Stockholders' Equity Preferred Stock Issuances (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	9 Months Ended		12 Months Ended
	Jul. 31, 2018	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Class of Stock [Line Items]
Preferred stock par value per share (in usd per share)		$ 0.01		$ 0.01
Proceeds from issuance of preferred stock, net of offering costs		$ 13	$ 416,966
Aggregate cash consideration exchanged for shares of CYS common stock	$ 14,967
Series A Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock dividend rate		8.125%
Preferred stock par value per share (in usd per share)		$ 0.01
Preferred stock public offering price per share (in usd per share)		25.00
Preferred stock liquidation preference per share (in usd per share)		$ 25.00
Preferred stock dividend variable rate spread		5.66%
Preferred stock redemption price per share (in usd per share)		$ 25.00
Proceeds from issuance of preferred stock, net of offering costs				$ 138,900
Series A Preferred Stock [Member] \| Public Offering [Member]
Class of Stock [Line Items]
Number of shares of stock issued during period (in shares)				5,000,000
Series A Preferred Stock [Member] \| Over-Allotment Option [Member]
Class of Stock [Line Items]
Number of shares of stock issued during period (in shares)				750,000
Series B Preferred Stock [Member]
Class of Stock [Line Items]
Number of shares of stock issued during period (in shares)				11,500,000
Preferred stock dividend rate		7.625%
Preferred stock par value per share (in usd per share)		$ 0.01
Preferred stock public offering price per share (in usd per share)		25.00
Preferred stock liquidation preference per share (in usd per share)		$ 25.00
Preferred stock dividend variable rate spread		5.352%
Preferred stock redemption price per share (in usd per share)		$ 25.00
Proceeds from issuance of preferred stock, net of offering costs				$ 278,100
Series B Preferred Stock [Member] \| Over-Allotment Option [Member]
Class of Stock [Line Items]
Number of shares of stock issued during period (in shares)				1,500,000
Series C Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock dividend rate		7.25%
Preferred stock par value per share (in usd per share)		$ 0.01
Preferred stock public offering price per share (in usd per share)		25.00
Preferred stock liquidation preference per share (in usd per share)		$ 25.00
Preferred stock dividend variable rate spread		5.011%
Preferred stock redemption price per share (in usd per share)		$ 25.00
Proceeds from issuance of preferred stock, net of offering costs				$ 285,600
Series C Preferred Stock [Member] \| Public Offering [Member]
Class of Stock [Line Items]
Number of shares of stock issued during period (in shares)				11,000,000
Series C Preferred Stock [Member] \| Over-Allotment Option [Member]
Class of Stock [Line Items]
Number of shares of stock issued during period (in shares)				800,000
Series D Preferred Stock [Member]
Class of Stock [Line Items]
Number of shares of stock issued during period (in shares)	3,000,000
Preferred stock dividend rate		7.75%
Preferred stock par value per share (in usd per share)		$ 0.01
Preferred stock liquidation preference per share (in usd per share)		25.00
Preferred stock redemption price per share (in usd per share)		$ 25.00
Series E Preferred Stock [Member]
Class of Stock [Line Items]
Number of shares of stock issued during period (in shares)	8,000,000
Preferred stock dividend rate		7.50%
Preferred stock par value per share (in usd per share)		$ 0.01
Preferred stock liquidation preference per share (in usd per share)		25.00
Preferred stock redemption price per share (in usd per share)		$ 25.00