XML 172 R95.htm IDEA: XBRL DOCUMENT v3.22.1
Income Taxes - Additional Information (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Income Taxes [Line Items]    
United States corporate tax at a rate 21.00%  
Increase (decrease) in valuation allowance $ 38.8 $ 37.9
Less valuation allowance 225.9 187.1
Deferred Tax Liabilities, Net 2.8 5.2
Deferred Tax Assets, Gross 277.5 240.7
Lloyd's | U.K.    
Income Taxes [Line Items]    
Deferred tax losses, operating loss carryforward 66.2 57.9
Other juridictions | U.K.    
Income Taxes [Line Items]    
Deferred tax losses, operating loss carryforward 103.9 46.8
U.K. operating companies    
Income Taxes [Line Items]    
Deferred tax liabilities and assets   48.1
Swiss branches of the UK operating companies    
Income Taxes [Line Items]    
Deferred Tax Liabilities, Net   5.4
Other Comprehensive Income | U.K.    
Income Taxes [Line Items]    
Less valuation allowance 27.5 4.8
Internal Revenue Service (IRS)    
Income Taxes [Line Items]    
Net operating loss carryforwards 443.1 526.4
Operating loss carryforwards, remaining 443.1  
Operating loss carryforwards, subject to expiration date 443.1  
Charitable contribution carryforwards 0.1 1.0
Less valuation allowance 119.7 119.2
Internal Revenue Service (IRS) | Aspen U.K.    
Income Taxes [Line Items]    
Operating loss carryforwards, subject to s382 limitation 6.5  
Internal Revenue Service (IRS) | U.S. operating subsidiaries    
Income Taxes [Line Items]    
Operating loss carryforwards, subject to s382 limitation $ 20.8  
Internal Revenue Service (IRS) | Minimum    
Income Taxes [Line Items]    
Operating loss carryforwards, date of expiration 2031  
Internal Revenue Service (IRS) | Maximum    
Income Taxes [Line Items]    
Operating loss carryforwards, date of expiration 2039  
U.K.    
Income Taxes [Line Items]    
U. K. corporate tax rate 19.00%  
Net operating loss carryforwards $ 168.9 101.8
Operating loss carryforwards, remaining 20.2 16.7
Capital loss carryforwards 3.8  
Less valuation allowance $ 88.7 58.6
Bermuda    
Income Taxes [Line Items]    
Bermuda tax rate 0.00%  
Valuation Allowance, Operating Loss Carryforwards | U.K.    
Income Taxes [Line Items]    
Less valuation allowance $ 9.6 40.8
Foreign Exchange | U.K.    
Income Taxes [Line Items]    
Less valuation allowance $ 1.7 $ 1.9