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

Quarterly report pursuant to Section 13 or 15(d)

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

Derivative Instruments and Hedging Activities Schedule of Interest Rate Swap Payers Associated with the Investment Portfolio (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Derivative [Line Items]
Derivative, Notional Amount	$ 33,709,043invest_DerivativeNotionalAmount	$ 48,115,523invest_DerivativeNotionalAmount	$ 43,576,146invest_DerivativeNotionalAmount	$ 37,366,610invest_DerivativeNotionalAmount
Interest Rate Swap [Member]
Derivative [Line Items]
Derivative, Notional Amount	19,929,000	18,584,000	21,663,148	19,619,000
Interest Rate Risk Associated with the Investment Portfolio [Member] \| Interest Rate Swap [Member] \| Long [Member]
Derivative [Line Items]
Derivative, Notional Amount	5,250,000	4,940,000
Derivative, Average Fixed Interest Rate	1.514%	1.512%
Derivative, Average Variable Interest Rate	0.261%	0.237%
Derivative, Average Remaining Period Until Maturity	3.65	3.80
Interest Rate Risk Associated with the Investment Portfolio [Member] \| Derivative Maturity Over Two And Within Three Years From Balance Sheet Date [Member] \| Interest Rate Swap [Member] \| Long [Member]
Derivative [Line Items]
Derivative, Notional Amount	2,000,000	2,000,000
Derivative, Average Fixed Interest Rate	1.07%	1.07%
Derivative, Average Variable Interest Rate	0.254%	0.229%
Derivative, Average Remaining Period Until Maturity	2.29	2.54
Interest Rate Risk Associated with the Investment Portfolio [Member] \| Derivative Maturity Over Three And Within Four Years From Balance Sheet Date [Member] \| Interest Rate Swap [Member] \| Long [Member]
Derivative [Line Items]
Derivative, Notional Amount	2,040,000	2,040,000
Derivative, Average Fixed Interest Rate	1.563%	1.563%
Derivative, Average Variable Interest Rate	0.265%	0.238%
Derivative, Average Remaining Period Until Maturity	3.69	3.94
Interest Rate Risk Associated with the Investment Portfolio [Member] \| Derivative Maturity Over Four Years From Balance Sheet Date [Member] \| Interest Rate Swap [Member] \| Long [Member]
Derivative [Line Items]
Derivative, Notional Amount	$ 1,210,000	$ 900,000
Derivative, Average Fixed Interest Rate	2.164%	2.378%
Derivative, Average Variable Interest Rate	0.265%	0.255%
Derivative, Average Remaining Period Until Maturity	5.83	6.24