Stock Repurchase Program	9 Months Ended
	Sep. 30, 2023
Stock Repurchase Program [Abstract]
Stock Repurchase Program	Stock Repurchase Program On March 30, 2021, the board of directors adopted a stock repurchase program pursuant to which Harbor was initially authorized to repurchase up to $1,000 of shares of its common stock during the first calendar month of the program, subject to an automatic increase of $1,000 per calendar month thereafter. Harbor is not obligated under the program to acquire any particular number or value of shares and can suspend or terminate the program at any time. In January 2023, a federal corporate stock repurchase excise tax of 1% took effect once share repurchases exceed $1,000. Harbor accrued an excise tax liability of $8 and $38 during the three and nine months ended September 30, 2023,respectively, which is included in the cost of Treasury stock on the condensed consolidated statements of stockholders’ equity. Harbor acquired a total of 374 and 1,764 shares of its common stock pursuant to the stock repurchase program in the three and nine months ended September 30, 2023, respectively, compared to 364 and 7,664 in the three and nine months ended September 30, 2022, respectively. As of September 30, 2023 and December 31, 2022, total cash of $329 and $475, respectively, was held for the repurchase of shares under Harbor’s stock repurchase program. This amount is included in restricted cash. For additional information, refer to Part II, Item 2, “Purchases of Equity Securities by the Issuer and Affiliated Purchasers” in this Quarterly Report.