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Variable Interest Entity and Noncontrolling Interests - Carrying amount of assets and liabilities of variable interest entity (Details) - USD ($) $ in Thousands | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
--- | --- | --- | --- | ---
Assets |  |  |  |
Investments accounted for using the fair value option | $ 3,824,796 | $ 3,663,477 |  |
Fixed maturities available for sale, at fair value | 18,717,825 | 16,894,526 |  |
Equity securities, at fair value | 1,444,830 | 838,925 |  |
Cash | 906,448 | 726,230 | $ 646,556 |
Accrued investment income | 103,299 | 117,937 |  |
Premiums receivable | 2,064,586 | 1,778,717 |  |
Ceded unearned premiums | 1,234,075 | 1,234,683 |  |
Deferred acquisition costs | 790,708 | 633,400 |  |
Receivable for securities sold | 92,743 | 24,133 |  |
Goodwill and intangible assets | 692,863 | 738,083 | 634,920 |
Other assets | 1,853,579 | 1,383,788 |  |
Total assets of consolidated VIE | 43,282,297 | 37,885,361 | 32,218,329 |
Liabilities |  |  |  |
Reserve for losses and loss adjustment expenses | 16,513,929 | 13,891,842 | 11,853,297 | $ 11,383,792
Unearned premiums | 4,838,965 | 4,339,549 |  |
Reinsurance balances payable | 683,263 | 667,072 |  |
Revolving credit agreement borrowings | 155,687 | 484,287 |  |
Senior notes | 2,861,113 | 1,871,626 |  |
Payable for securities purchased | 218,779 | 87,579 |  |
Other liabilities | 1,510,888 | 1,513,330 |  |
Total liabilities of consolidated VIE | 29,294,856 | 25,569,809 | $ 21,780,650 |
Watford Holdings Ltd | Variable Interest Entity, Primary Beneficiary |  |  |  |
Assets |  |  |  |
Investments accounted for using the fair value option | 1,790,385 | 1,898,091 |  |
Fixed maturities available for sale, at fair value | 655,249 | 745,708 |  |
Equity securities, at fair value | 52,410 | 65,338 |  |
Cash | 211,451 | 102,437 |  |
Accrued investment income | 14,679 | 14,025 |  |
Premiums receivable | 224,377 | 273,657 |  |
Reinsurance recoverable on unpaid and paid losses and loss adjustment expenses | 286,590 | 170,973 |  |
Ceded unearned premiums | 122,339 | 132,577 |  |
Deferred acquisition costs | 53,705 | 64,044 |  |
Receivable for securities sold | 37,423 | 16,287 |  |
Goodwill and intangible assets | 7,650 | 7,650 |  |
Other assets | 75,801 | 60,070 |  |
Total assets of consolidated VIE | 3,532,059 | 3,550,857 |  |
Liabilities |  |  |  |
Reserve for losses and loss adjustment expenses | 1,519,583 | 1,263,628 |  |
Unearned premiums | 407,714 | 438,907 |  |
Reinsurance balances payable | 63,269 | 77,066 |  |
Revolving credit agreement borrowings | 155,687 | 484,287 |  |
Senior notes | 172,689 | 172,418 |  |
Payable for securities purchased | 25,881 | 18,180 |  |
Other liabilities | 193,494 | 171,714 |  |
Total liabilities of consolidated VIE | 2,538,317 | 2,626,200 |  |
Redeemable noncontrolling interests | $ 52,398 | $ 52,305 |  |

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- Definition Amount, after valuation allowance, recoverable under reinsurance contracts including premium paid under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, premium paid, policy benefits and policy reserves. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(6)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 20 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=99397103&loc=d3e6824-158387 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 310 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=99404803&loc=d3e21409-158489 + Details
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- Definition Carrying value as of the balance sheet date of Notes with the highest claim on the assets of the issuer in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle if longer), excluding current portion. Senior note holders are paid off in full before any payments are made to junior note holders. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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- Definition Carrying amount of premiums written on insurance contracts that have not been earned as of the balance sheet date. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(13)(a)(2)) -URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910 + Details
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