{"pre_text": ["uncertain tax positions the following is a reconciliation of the company 2019s beginning and ending amount of uncertain tax positions ( in millions ) : ."], "post_text": ["the company 2019s liability for uncertain tax positions as of december 31 , 2018 , 2017 , and 2016 , includes $ 228 million , $ 219 million , and $ 240 million , respectively , related to amounts that would impact the effective tax rate if recognized .", "it is possible that the amount of unrecognized tax benefits may change in the next twelve months ; however , the company does not expect the change to have a significant impact on its consolidated statements of income or consolidated balance sheets .", "these changes may be the result of settlements of ongoing audits .", "at this time , an estimate of the range of the reasonably possible outcomes within the twelve months cannot be made .", "the company recognizes interest and penalties related to uncertain tax positions in its provision for income taxes .", "the company accrued potential interest and penalties of $ 22 million , $ 11 million , and $ 15 million in 2018 , 2017 , and 2016 , respectively .", "the company recorded a liability for interest and penalties of $ 77 million , $ 55 million , and $ 48 million as of december 31 , 2018 , 2017 , and 2016 , respectively .", "the company and its subsidiaries file income tax returns in their respective jurisdictions .", "the company has substantially concluded all u.s .", "federal income tax matters for years through 2007 .", "material u.s .", "state and local income tax jurisdiction examinations have been concluded for years through 2005 .", "the company has concluded income tax examinations in its primary non-u.s .", "jurisdictions through 2010 .", "12 .", "shareholders 2019 equityq y distributable reserves as a company incorporated in england and wales , aon is required under u.k .", "law to have available 201cdistributable reserves 201d to make share repurchases or pay dividends to shareholders .", "distributable reserves may be created through the earnings of the u.k .", "parent company and , among other methods , through a reduction in share capital approved by the courts of england and wales .", "distributable reserves are not directly linked to a u.s .", "gaap reported amount ( e.g. , retained earnings ) .", "as of december 31 , 2018 and 2017 , the company had distributable reserves in excess of $ 2.2 billion and $ 1.2 billion , respectively .", "ordinary shares aon has a share repurchase program authorized by the company 2019s board of directors ( the 201crepurchase program 201d ) .", "the repurchase program was established in april 2012 with $ 5.0 billion in authorized repurchases , and was increased by $ 5.0 billion in authorized repurchases in each of november 2014 and february 2017 for a total of $ 15.0 billion in repurchase authorizations .", "under the repurchase program , class a ordinary shares may be repurchased through the open market or in privately negotiated transactions , from time to time , based on prevailing market conditions , and will be funded from available capital. ."], "table": [["", "2018", "2017"], ["balance at january 1", "$ 280", "$ 278"], ["additions based on tax positions related to the current year", "18", "25"], ["additions for tax positions of prior years", "10", "12"], ["reductions for tax positions of prior years", "-24 ( 24 )", "-26 ( 26 )"], ["settlements", "2014", "-6 ( 6 )"], ["business combinations", "1", "2014"], ["lapse of statute of limitations", "-6 ( 6 )", "-7 ( 7 )"], ["foreign currency translation", "2014", "4"], ["balance at december 31", "$ 279", "$ 280"]], "table_ori": [["", "2018", "2017"], ["Balance at January 1", "$280", "$278"], ["Additions based on tax positions related to the current year", "18", "25"], ["Additions for tax positions of prior years", "10", "12"], ["Reductions for tax positions of prior years", "(24)", "(26)"], ["Settlements", "—", "(6)"], ["Business combinations", "1", "—"], ["Lapse of statute of limitations", "(6)", "(7)"], ["Foreign currency translation", "—", "4"], ["Balance at December 31", "$279", "$280"]]}

Question: what is the decrease observed in the additions for tax positions of prior years , in millions?
Evidence:
table_3: the additions for tax positions of prior years of 2018 is 10 ; the additions for tax positions of prior years of 2017 is 12 ;
Program: subtract(12, 10)
Answer:
str_answer: 2
exe_answer: 2