Significant Accounting Policies (Policies)	9 Months Ended
Sep. 30, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation: The interim condensed consolidated financial statements are unaudited. Because of the nature of the Company's operations, the results for interim periods are not necessarily indicative of results to be expected for the year. While these condensed consolidated financial statements reflect all normal recurring adjustments that are, in the opinion of management, necessary for fair presentation of the results of the interim period, they do not include all of the information and footnotes required by accounting principles generally accepted in the United States of America ("GAAP") for complete financial statements. Therefore, the interim condensed consolidated financial statements should be read in conjunction with the consolidated balance sheets as of December 31, 2022 and 2021, and the related consolidated statements of operations, comprehensive income (loss), cash flows, and equity and redeemable noncontrolling interest for each of the three years ended December 31, 2022, 2021, and 2020, respectively, and the notes thereto included in the Company's Annual Report filed on Form 10-K for the year ended December 31, 2022 ("2022 Form 10-K"), and other subsequent filings with the U.S. Securities and Exchange Commission ("SEC").
Reclassifications	Reclassifications: Prior to December 31, 2022, the Company operated and reported on three segments: Commercial Real Estate; Land Operations; and Materials & Construction ("M&C"). During the fourth quarter of 2022, the Company's wholly-owned subsidiary, Grace Pacific LLC ("Grace Pacific") and Company-owned quarry land on Maui ("Maui Quarries") (collectively, the "Grace Disposal Group"), which made up the majority of activity in the Company’s former M&C segment, met the criteria for classification as held for sale and discontinued operations. Accordingly, the assets and liabilities associated with the Grace Disposal Group are classified as held for sale in the condensed consolidated balance sheets, its financial results are classified as discontinued operations in the condensed consolidated statements of operations and cash flows for all periods presented, and the Company’s former Materials and Construction ("M&C") segment has been eliminated. As a result of this strategic shift, the chief operating decision maker began reviewing all investments in unconsolidated affiliates together within the Land Operations segment. This change resulted in a reorganization to present the income (loss) related to one joint venture, which historically was included in the results of the former M&C segment, to now be included in the results of the Land Operations segment. All comparable information for the historical periods has been retrospectively adjusted to reflect the impact of these changes. Refer to Note 18 – Held for Sale and Discontinued Operations for additional information regarding the Grace Disposal Group, including the assets held for sale, liabilities associated with held for sale and income (loss) from discontinued operations. Unless otherwise noted, disclosures within the remaining notes to these condensed consolidated financial statements relate solely to the Company's continuing operations.
Rounding	Rounding: Amounts in the condensed consolidated financial statements and notes are rounded to the nearest tenth of a million. Accordingly, a recalculation of some per-share amounts and percentages, if based on the reported data, may result in differences.
Recently issued accounting pronouncements	Recently issued accounting pronouncements In March 2020, the FASB issued Accounting Standards Update ("ASU") No. 2020-04, Reference Rate Reform, establishing ASC Topic 848, and amended the standard thereafter through ASU No. 2021-01 and ASU No. 2022-06 (collectively, "ASC 848"). ASC 848 provides optional practical expedients and exceptions related to the impacts of reference rate reform that affect certain debt, leases, derivatives and other contracts if certain criteria are met. The amendments apply only to contracts and hedging relationships that reference London Interbank Offered Rate ("LIBOR") or another reference rate expected to be discontinued due to reference rate reform. These amendments are effective immediately and may be applied prospectively to contract modifications made and hedging relationships entered into or evaluated on or before December 31, 2024. The Company adopted ASU 2020-04 during the second quarter of 2023 after modifying certain debt to update the reference rate from LIBOR to the Secured Overnight Financing Rate ("SOFR"). The Company will continue to assess the impact of the guidance and may apply other elections as applicable going forward but does not expect the application will have a material effect on its financial position or results of operations.

Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2023

Basis of Presentation: The interim condensed consolidated financial statements are unaudited. Because of the nature of the Company's operations, the results for interim periods are not necessarily indicative of results to be expected for the year. While these condensed consolidated financial statements reflect all normal recurring adjustments that are, in the opinion of management, necessary for fair presentation of the results of the interim period, they do not include all of the information and footnotes required by accounting principles generally accepted in the United States of America ("GAAP") for complete financial statements. Therefore, the interim condensed consolidated financial statements should be read in conjunction with the consolidated balance sheets as of December 31, 2022 and 2021, and the related consolidated statements of operations, comprehensive income (loss), cash flows, and equity and redeemable noncontrolling interest for each of the three years ended December 31, 2022, 2021, and 2020, respectively, and the notes thereto included in the Company's Annual Report filed on Form 10-K for the year ended December 31, 2022 ("2022 Form 10-K"), and other subsequent filings with the U.S. Securities and Exchange Commission ("SEC").

Reclassifications

Reclassifications: Prior to December 31, 2022, the Company operated and reported on three segments: Commercial Real Estate; Land Operations; and Materials & Construction ("M&C"). During the fourth quarter of 2022, the Company's wholly-owned subsidiary, Grace Pacific LLC ("Grace Pacific") and Company-owned quarry land on Maui ("Maui Quarries") (collectively, the "Grace Disposal Group"), which made up the majority of activity in the Company’s former M&C segment, met the criteria for classification as held for sale and discontinued operations. Accordingly, the assets and liabilities associated with the Grace Disposal Group are classified as held for sale in the condensed consolidated balance sheets, its financial results are classified as discontinued operations in the condensed consolidated statements of operations and cash flows for all periods presented, and the Company’s former Materials and Construction ("M&C") segment has been eliminated. As a result of this strategic shift, the chief operating decision maker began reviewing all investments in unconsolidated affiliates together within the Land Operations segment. This change resulted in a reorganization to present the income (loss) related to one joint venture, which historically was included in the results of the former M&C segment, to now be included in the results of the Land Operations segment. All comparable information for the historical periods has been retrospectively adjusted to reflect the impact of these changes. Refer to Note 18 – Held for Sale and Discontinued Operations for additional information regarding the Grace Disposal Group, including the assets held for sale, liabilities associated with held for sale and income (loss) from discontinued operations. Unless otherwise noted, disclosures within the remaining notes to these condensed consolidated financial statements relate solely to the Company's continuing operations.

Rounding

Rounding: Amounts in the condensed consolidated financial statements and notes are rounded to the nearest tenth of a million. Accordingly, a recalculation of some per-share amounts and percentages, if based on the reported data, may result in differences.

Recently issued accounting pronouncements

In March 2020, the FASB issued Accounting Standards Update ("ASU") No. 2020-04, Reference Rate Reform, establishing ASC Topic 848, and amended the standard thereafter through ASU No. 2021-01 and ASU No. 2022-06 (collectively, "ASC 848"). ASC 848 provides optional practical expedients and exceptions related to the impacts of reference rate reform that affect certain debt, leases, derivatives and other contracts if certain criteria are met. The amendments apply only to contracts and hedging relationships that reference London Interbank Offered Rate ("LIBOR") or another reference rate expected to be discontinued due to reference rate reform. These amendments are effective immediately and may be applied prospectively to contract modifications made and hedging relationships entered into or evaluated on or before December 31, 2024. The Company adopted ASU 2020-04 during the second quarter of 2023 after modifying certain debt to update the reference rate from LIBOR to the Secured Overnight Financing Rate ("SOFR"). The Company will continue to assess the impact of the guidance and may apply other elections as applicable going forward but does not expect the application will have a material effect on its financial position or results of operations.