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

Schedule of Underlying Assets of Repurchase Agreements when Amount of Repurchase Agreements Exceeds 10 Percent of Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Assets Sold under Agreements to Repurchase [Line Items]
Assets pledged or restricted as collateral for repurchase agreements	$ 21,859,645	$ 25,530,229
Available-for-sale Securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Assets pledged or restricted as collateral for repurchase agreements	20,925,201	24,240,507
Mortgage Servicing Rights [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Assets pledged or restricted as collateral for repurchase agreements	756,573	685,683
Restricted Cash and Cash Equivalents [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Assets pledged or restricted as collateral for repurchase agreements	66,296	416,696
Due From Counterparties [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Assets pledged or restricted as collateral for repurchase agreements	35,619	110,695
Derivative Financial Instruments, Assets [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Assets pledged or restricted as collateral for repurchase agreements	71,696	70,191
US Treasury Securities [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Assets pledged or restricted as collateral for repurchase agreements	$ 4,260	$ 6,457