pre_text: A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows (in millions): As of April 26, 2019, we had $296 million of gross unrecognized tax benefits, of which $252 million has been recorded in other long-term liabilities. Unrecognized tax benefits of $246 million, including penalties, interest and indirect benefits, would affect our provision for income taxes if recognized. As a result of U.S. tax reform, we recorded provisional gross unrecognized tax benefits of $114 million during fiscal 2018. We recognized a benefit for adjustments to accrued interest and penalties related to unrecognized tax benefits in the income tax provision of approximately $4 million in fiscal 2019 and expense of $5 million in each of fiscal 2018 and 2017. Accrued interest and penalties of $18 million and $22 million were recorded in the consolidated balance sheets as of April 26, 2019 and April 27, 2018, respectively.
table: Year Ended
table: April 26, 2019 April 27, 2018 April 28, 2017
table: Balance at beginning of period $ 348 $ 218 $ 216
table: Additions based on tax positions related to the current year 11 131 7
table: Additions for tax positions of prior years 26 — 7
table: Decreases for tax positions of prior years (35 ) (1 ) —
table: Settlements (54 ) — (12 )
table: Balance at end of period $ 296 $ 348 $ 218
question: Analyse this data from a financial earnings document. What was the change in the Balance at beginning of period between 2017 and 2018?