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

Derivative Instruments and Hedging Activities Put and Call Options for TBAs (Details) - USD ($)	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Notional	$ 18,429,288,000	$ 31,226,878,000	$ 15,935,535,000	$ 18,802,500,000
Derivative Financial Instruments, Assets [Member]
Derivative [Line Items]
Notional	25,956,767,000	25,503,371,000
Fair Value	274,048,000	309,918,000
Derivative Financial Instruments, Liabilities [Member]
Derivative [Line Items]
Notional	12,752,521,000	8,335,507,000
Fair Value	(46,074,000)	(31,903,000)
Options Held [Member] \| Derivative Financial Instruments, Assets [Member]
Derivative [Line Items]
Notional	785,000,000
Fair Value	872,000	0
Options Held [Member] \| Derivative Financial Instruments, Liabilities [Member]
Derivative [Line Items]
Notional	845,000,000
Fair Value	(6,957,000)	0
Options Held [Member] \| Long [Member]
Derivative [Line Items]
Notional	7,573,000,000	0
Options Held [Member] \| Short [Member]
Derivative [Line Items]
Notional	$ 7,600,000,000	$ 0