Task: Table-QA (source dataset: FinQA)

Task: 
You are given a table containing structured data and a natural language question referring to the table. Your goal is to analyze the table and provide an accurate and concise answer based on the given data.

Instructions:
1. Understand the Table: Examine the structure, headers, and data in the table. Identify relevant columns and rows related to the question.
2. Interpret the Question: Determine whether the question requires direct retrieval, aggregation, comparison, sorting, filtering, or inference.
3. Extract the Answer: Use logical reasoning and numerical operations (if necessary) to derive the correct response from the table.
4. Format the Answer: No explanation, return the answer in a structured JSON format: {"answer": <answer>}. If the question cannot be answered due to missing or ambiguous data, return a JSON response with {"answer": null}.

Table:
| Unnamed: 0                                                   | 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      |

Question:
what is the decrease observed in the additions for tax positions of prior years , in millions?


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. .
label: 2
qa: answer: 2
explanation: it is the difference between those values .
ann_table_rows: 3
steps: op: minus2-1
arg1: 12
arg2: 10
res: 2
program: subtract(12, 10)
gold_inds: 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 ;
exe_ans: 2
tfidftopn: table_4: The reductions for tax positions of prior years of 2018 is -24 ( 24 ) ; The reductions for tax positions of prior years of 2017 is -26 ( 26 ) ;
text_0: uncertain tax positions the following is a reconciliation of the company 2019s beginning and ending amount of uncertain tax positions ( in millions ) : .
program_re: subtract(12, 10)
model_input: table_2
the additions based on tax positions related to the current year of 2018 is 18 ; the additions based on tax positions related to the current year of 2017 is 25 ;
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 ;
table_9
the balance at december 31 of 2018 is $ 279 ; the balance at december 31 of 2017 is $ 280 ;