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

Derivative Instruments and Hedging Activities Schedule of Interest Rate Swap Receivers Associated with the Investment Portfolio (Details)

Derivative Instruments and Hedging Activities Schedule of Interest Rate Swap Receivers Associated with the Investment Portfolio (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Derivative [Line Items]
Derivative, Notional Amount	$ 48,115,523invest_DerivativeNotionalAmount	$ 37,366,610invest_DerivativeNotionalAmount	$ 22,377,656invest_DerivativeNotionalAmount
Interest Rate Swap [Member]
Derivative [Line Items]
Derivative, Notional Amount	18,584,000	19,619,000	14,070,000
Interest Rate Swap [Member] \| Interest Rate Risk Associated with the Investment Portfolio [Member] \| Short [Member]
Derivative [Line Items]
Derivative, Notional Amount	2,154,000	2,154,000
Derivative, Average Variable Interest Rate	2.433%	2.337%
Derivative, Average Fixed Interest Rate	0.237%	0.24%
Derivative, Average Remaining Period Until Maturity	7.77	7.84
Interest Rate Swap [Member] \| Interest Rate Risk Associated with the Investment Portfolio [Member] \| Derivative Maturity Over Four Years From Balance Sheet Date [Member] \| Short [Member]
Derivative [Line Items]
Derivative, Notional Amount	1,579,000	2,154,000
Derivative, Average Variable Interest Rate	2.794%	2.337%
Derivative, Average Fixed Interest Rate	0.239%	0.24%
Derivative, Average Remaining Period Until Maturity	9.19	7.84
Interest Rate Swap [Member] \| Interest Rate Risk Associated with the Investment Portfolio [Member] \| Derivative Maturity Over Three And Within Four Years From Balance Sheet Date [Member] \| Short [Member]
Derivative [Line Items]
Derivative, Notional Amount	$ 575,000
Derivative, Average Variable Interest Rate	1.44%
Derivative, Average Fixed Interest Rate	0.231%
Derivative, Average Remaining Period Until Maturity	3.89