TWO Annual report pursuant to Section 13 and 15(d)

Derivative Instruments and Hedging Activities Put and Call Options for TBAs (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative [Line Items]
Notional	$ 31,226,878,000	$ 18,802,500,000	$ 21,998,381,000
Derivative Financial Instruments, Assets [Member]
Derivative [Line Items]
Notional	25,503,371,000	21,708,907,000
Fair Value	309,918,000	324,182,000
Options Held [Member] \| Derivative Financial Instruments, Assets [Member]
Derivative [Line Items]
Notional		1,136,000,000
Fair Value	0	42,633,000
Options Held [Member] \| Long [Member]
Derivative [Line Items]
Notional	$ 0	2,500,000,000
Options Held [Member] \| Short [Member]
Derivative [Line Items]
Notional		$ 3,636,000,000