Quarterly report pursuant to Section 13 or 15(d)

Schedule of Repurchase Agreement Counterparties with Whom Repurchase Agreements Exceed 10 Percent of Stockholders' Equity (Details)

v3.10.0.1
Schedule of Repurchase Agreement Counterparties with Whom Repurchase Agreements Exceed 10 Percent of Stockholders' Equity (Details)
$ in Thousands
9 Months Ended 12 Months Ended
Sep. 30, 2018
USD ($)
counterparty
Dec. 31, 2017
USD ($)
counterparty
Repurchase Agreement Counterparty [Line Items]    
Repurchase agreements $ 23,806,631 $ 19,451,207
Net Counterparty Exposure $ 1,906,556 $ 1,743,123
Weighted Average Days to Maturity 92 days 83 days
Payables due to counterparties for unsettled securities purchases $ 421,100 $ 0
Repurchase Agreement Counterparty, Royal Bank of Canada [Member]    
Repurchase Agreement Counterparty [Line Items]    
Repurchase agreements 1,898,455 1,261,956
Net Counterparty Exposure $ 316,471 $ 223,347
Percent of Equity 7.00% 6.00%
Weighted Average Days to Maturity 146 days 75 days
Repurchase Agreement Counterparty, All Other Counterparties [Member]    
Repurchase Agreement Counterparty [Line Items]    
Repurchase agreements $ 21,908,176 $ 18,189,251
Net Counterparty Exposure $ 1,590,085 $ 1,519,776
Percent of Equity 34.00% 43.00%
Weighted Average Days to Maturity 87 days 84 days
Number of repurchase agreement counterparties with whom amount at risk is less than 10 percent of stockholders' equity | counterparty 34 26