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Variable Interest Entity and Noncontrolling Interests - Redeemable noncontrolling interest (Details) - USD ($) $ / shares in Units, $ in Thousands |  | 3 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Aug. 01, 2019 | Mar. 31, 2015 | Mar. 31, 2014 | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | Jul. 31, 2019
Redeemable Noncontrolling Interest [Line Items] |  |  |  |  |  |  |
Balance, beginning of year |  |  |  | $ 55,404 | $ 206,292 | $ 205,922 |
Redemption of noncontrolling interests |  |  |  | 0 | (157,709) | 0 |
Accretion of preference share issuance costs |  |  |  | 93 | 244 | 370 |
Other |  |  |  | 3,051 | 6,577 | 0 |
Balance, end of year |  |  |  | $ 58,548 | 55,404 | 206,292 |
Preferred shares, par value per share |  |  |  | $ 0.01 |  |  |
Watford Holdings Ltd |  |  |  |  |  |  |
Redeemable Noncontrolling Interest [Line Items] |  |  |  |  |  |  |
Preferred dividends including accretion of discount and issuance costs |  |  |  | $ 4,400 | $ 17,800 | $ 19,600 |
Variable Interest Entity, Primary Beneficiary | Watford Holdings Ltd |  |  |  |  |  |  |
Redeemable Noncontrolling Interest [Line Items] |  |  |  |  |  |  |
Preference shares, number of shares issued |  |  |  |  |  |  | 9,065,200
Shares redeemed during the period, shares | 6,919,998 |  |  |  |  |  |
Preferred shares, redemption price per share | $ 25.19748 |  |  |  |  |  |
Proceeds from Redemption Of Preferred Shares By Variable Interest Entity | $ 11,500 |  |  |  |  |  |
Redeemable Preferred Stock [Member] | Watford Holdings Ltd |  |  |  |  |  |  |
Redeemable Noncontrolling Interest [Line Items] |  |  |  |  |  |  |
Preferred shares, par value per share |  |  | $ 0.01 |  |  |  |
Liquidation preference per share |  |  | 25.00 |  |  |  |
Shares Issued, Price Per Share |  |  | $ 24.50 |  |  |  |
Preferred shares, dividend rate (as a percent) |  |  | 8.50% |  |  |  |
Redeemable Preferred Stock [Member] | 3 month US dollar LIBOR | Watford Holdings Ltd |  |  |  |  |  |  |
Redeemable Noncontrolling Interest [Line Items] |  |  |  |  |  |  |
Preferred shares, dividend rate (as a percent) |  | 1.00% |  |  |  |  |

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- Definition The per share liquidation preference (or restrictions) of nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) that has a preference in involuntary liquidation considerably in excess of the par or stated value of the shares. The liquidation preference is the difference between the preference in liquidation and the par or stated values of the share. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08(d)) -URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644 Reference 3: 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(28)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21484-112644 + Details
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