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Investments - Amortized Cost and Fair Values of Debt Securities (Details) - USD ($) $ in Thousands | Jun. 30, 2021 | Dec. 31, 2020
--- | --- | ---
Amortized cost |  |
Due in one year or less | $ 449,359 |
Due after one year through five years | 1,870,031 |
Due after five years through ten years | 1,586,713 |
Due after ten years | 1,530,063 |
Total debt securities with single maturity date, amortized cost | 5,436,166 |
Amortized Cost | 6,682,052 | $ 6,317,164
Fair Value |  |
Due in one year or less | 453,780 |
Due after one year through five years | 1,939,373 |
Due after five years through ten years | 1,690,066 |
Due after ten years | 1,621,862 |
Total debt securities with single maturity date, fair value | 5,705,081 |
Total at end of period | 6,964,409 | 6,661,596
ABS |  |
Amortized cost |  |
Total debt securities without single maturity date, amortized cost | 154,031 |
Amortized Cost | 154,031 | 203,807
Fair Value |  |
Total debt securities without single maturity date, fair value | 155,733 |
Total at end of period | 155,733 | 206,686
RMBS |  |
Amortized cost |  |
Total debt securities without single maturity date, amortized cost | 377,315 |
Amortized Cost | 377,315 | 425,532
Fair Value |  |
Total debt securities without single maturity date, fair value | 379,203 |
Total at end of period | 379,203 | 431,166
CMBS |  |
Amortized cost |  |
Total debt securities without single maturity date, amortized cost | 318,470 |
Amortized Cost | 318,470 | 312,572
Fair Value |  |
Total debt securities without single maturity date, fair value | 327,435 |
Total at end of period | 327,435 | 327,502
CLOs |  |
Amortized cost |  |
Total debt securities without single maturity date, amortized cost | 396,070 |
Amortized Cost | 396,070 | 310,616
Fair Value |  |
Total debt securities without single maturity date, fair value | 396,957 |
Total at end of period | $ 396,957 | $ 310,490

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- Definition This item represents the total debt securities, categorized neither as held-to-maturity nor trading securities, which have a single maturity date, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments, as defined), and fair value hedge accounting adjustments, if any. + References No definition available. + Details
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- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454 + Details
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- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth through tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27198-111563 + Details
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- Definition Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth through tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27198-111563 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 320 -Section 50 -Paragraph 3A -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=123599081&loc=SL120269850-112803 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563 + Details
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- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27198-111563 + Details
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- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing after tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27198-111563 + Details
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