Annual report pursuant to Section 13 and 15(d)

Available-for-Sale Securities Classified by Rate Type (Details)

v2.4.1.9
Available-for-Sale Securities Classified by Rate Type (Details) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities, at fair value $ 14,341,102us-gaap_AvailableForSaleSecurities $ 12,256,727us-gaap_AvailableForSaleSecurities
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Adjustable Rate 128,285two_AvailableForSaleSecuritiesAdjustableRate
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember 		1,006,621two_AvailableForSaleSecuritiesAdjustableRate
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Available-for-sale Securities, Fixed Rate 11,164,032two_AvailableForSaleSecuritiesFixedRate
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember 		8,490,788two_AvailableForSaleSecuritiesFixedRate
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Available-for-sale securities, at fair value 11,292,317us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember 		9,497,409us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Mortgage-backed Securities, Issued by Private Enterprises [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Adjustable Rate 2,558,832two_AvailableForSaleSecuritiesAdjustableRate
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember 		2,403,078two_AvailableForSaleSecuritiesAdjustableRate
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember
Available-for-sale Securities, Fixed Rate 489,953two_AvailableForSaleSecuritiesFixedRate
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember 		356,240two_AvailableForSaleSecuritiesFixedRate
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember
Available-for-sale securities, at fair value 3,048,785us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember 		2,759,318us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesIssuedByPrivateEnterprisesMember
Collateralized Mortgage Backed Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Adjustable Rate 2,687,117two_AvailableForSaleSecuritiesAdjustableRate
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesMember 		3,409,699two_AvailableForSaleSecuritiesAdjustableRate
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesMember
Available-for-sale Securities, Fixed Rate 11,653,985two_AvailableForSaleSecuritiesFixedRate
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesMember 		8,847,028two_AvailableForSaleSecuritiesFixedRate
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesMember
Available-for-sale securities, at fair value $ 14,341,102us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesMember 		$ 12,256,727us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_MortgageBackedSecuritiesMember