Available-for-sale Securities Classified by Rate Type (Details) - USD ($) $ in Thousands |
Dec. 31, 2020 |
Dec. 31, 2019 |
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| Debt Securities, Available-for-sale [Line Items] | ||
| Adjustable Rate | $ 22,594 | $ 3,358,871 |
| Fixed Rate | 14,628,328 | 28,047,457 |
| Available-for-sale securities, at fair value | 14,650,922 | 31,406,328 |
| Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | ||
| Debt Securities, Available-for-sale [Line Items] | ||
| Adjustable Rate | 10,794 | 14,584 |
| Fixed Rate | 14,627,097 | 27,763,471 |
| Available-for-sale securities, at fair value | 14,637,891 | 27,778,055 |
| Mortgage-backed Securities, Issued by Private Enterprises [Member] | ||
| Debt Securities, Available-for-sale [Line Items] | ||
| Adjustable Rate | 11,800 | 3,344,287 |
| Fixed Rate | 1,231 | 283,986 |
| Available-for-sale securities, at fair value | $ 13,031 | $ 3,628,273 |
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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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