Available-for-sale Securities Classified by Rate Type (Details) - USD ($) $ in Thousands |
Sep. 30, 2018 |
Dec. 31, 2017 |
|---|---|---|
| Debt Securities, Available-for-sale [Line Items] | ||
| Adjustable Rate | $ 3,466,226 | $ 2,645,930 |
| Fixed Rate | 22,472,690 | 18,574,889 |
| Available-for-sale securities, at fair value | 25,938,916 | 21,220,819 |
| Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | ||
| Debt Securities, Available-for-sale [Line Items] | ||
| Adjustable Rate | 19,594 | 23,220 |
| Fixed Rate | 22,099,352 | 18,215,505 |
| Available-for-sale securities, at fair value | 22,118,946 | 18,238,725 |
| Mortgage-backed Securities, Issued by Private Enterprises [Member] | ||
| Debt Securities, Available-for-sale [Line Items] | ||
| Adjustable Rate | 3,446,632 | 2,622,710 |
| Fixed Rate | 373,338 | 359,384 |
| Available-for-sale securities, at fair value | $ 3,819,970 | $ 2,982,094 |
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- Definition This item represents investments in debt and equity securities with adjustable coupon rates which are categorized neither as held-to-maturity nor trading. No definition available.
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- Definition This item represents investments in debt and equity securities with fixed coupon rates which are categorized neither as held-to-maturity nor trading. No definition available.
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- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
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