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Income Taxes - Additional Information (Detail)
£ in Millions
12 Months Ended
Dec. 31, 2021
USD ($)
Dec. 31, 2020
USD ($)
Dec. 31, 2019
Dec. 31, 2017
Dec. 31, 2021
GBP (£)
Statutory federal corporate income tax rate 21.00% 21.00% 21.00% 34.00%  
Changes in valuation allowance $ 15,748,000 $ 13,068,000      
Unrecognized tax benefits 0 0      
Accrued penalties or interest related to uncertain tax positions 0 $ 0      
U.S. Federal [Member]          
Operating loss carry forwards 301,200,000        
Net operating loss carry forwards $ 151,800,000        
Operating loss carry forwards, expiration range start dates 2023        
Operating loss carry forwards, expiration range end dates 2038        
Tax years that remain subject to examination 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020        
State [Member]          
Operating loss carry forwards $ 222,600,000        
Operating loss carry forwards, expiration range start dates 2033        
Operating loss carry forwards, expiration range end dates 2038        
United Kingdom Tax Authority [Member]          
Operating loss carry forwards $ 27,600,000       £ 20.9
Tax years that remain subject to examination 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020        
Federal and State Research and Development Tax Credit Carryforward [Member]          
Research and development tax credit carry forwards $ 5,700,000        
Federal And State Tax [Member]          
Research and development tax credit carry forwards expiration begin date 2021        
Research and development tax credit carry forwards expiration end date 2038        
Icon Bioscience Inc [Member] | U.S. Federal [Member]          
Operating loss carry forwards $ 49,300,000