pre_text: The Company maintains a general allowance for doubtful accounts based on historical experience, along with additional customer specific allowances. The Company regularly monitors credit risk exposures in consolidated receivables. In estimating the necessary level of our allowance for doubtful accounts, management considers the aging of accounts receivable, the creditworthiness of customers, economic conditions within the customer’s industry, and general economic conditions, among other factors. The following reflects activity in the Company’s allowance for doubtful accounts receivable for the periods indicated (in thousands): Provision increases recorded in general and administrative expense during the years ended December 31, 2019, 2018, and 2017, reflect increases in the allowance for doubtful accounts based upon collection experience in the geographic regions in which the Company conducts business, net of collection of customer-specific receivables that were previously reserved for as doubtful of collection.
table: Years Ended December 31,
table: 2019 2018 2017
table: Balance, beginning of period -$3,912 -$4,799 -$3,873
table: Provision increase -2,561 -1,505 -2,086
table: Amounts written off, net of recoveries 1,368 2,269 1,305
table: Foreign currency translation adjustments and other -44 123 -145
table: Balance, end of period -$5,149 -$3,912 -$4,799
question: Analyse this data from a financial earnings document. What was the change in balance at the end of period between 2018 and 2019?