Summary of Significant Accounting Policies	3 Months Ended
Mar. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The accompanying condensed consolidated financial statements of EQC have been prepared without audit. Certain information and footnote disclosures required by U.S. generally accepted accounting principles, or GAAP, for complete financial statements have been condensed or omitted. We believe the disclosures made are appropriate. The accompanying condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes contained in our Annual Report on Form 10-K, or our Annual Report, for the year ended December 31, 2018. Capitalized terms used, but not defined in this Quarterly Report, have the same meanings as in our Annual Report. In the opinion of our management, all adjustments, which include only normal recurring adjustments considered necessary for a fair presentation, have been included. All intercompany transactions and balances with or among our subsidiaries have been eliminated. Operating results for interim periods are not necessarily indicative of the results that may be expected for the full year. Certain reclassifications have been made to the prior year's financial statements to conform to the current year’s presentation. The preparation of financial statements in conformity with GAAP requires us to make estimates and assumptions that affect reported amounts. Actual results could differ from those estimates. Significant estimates in the condensed consolidated financial statements include the assessment of the collectability of rental revenue, purchase price allocations, useful lives of fixed assets and impairment of real estate and intangible assets. Share amounts are presented in whole numbers, except where noted. Recent Accounting Pronouncements In August 2018, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement, which changes the fair value measurement disclosure requirements of FASB Accounting Standards Codification, or ASC, 820. This update is effective for fiscal years beginning after December 15, 2019, and for interim periods within those fiscal years. We do not expect the adoption of ASU 2018-13 to have a material impact on our consolidated financial statements. In June 2018, the FASB issued ASU 2018-07, Improvements to Nonemployee Share-Based Payment Accounting, which simplifies the accounting for share-based payments granted to nonemployees for goods and services. This update is effective for fiscal years beginning after December 15, 2018, and for interim periods within those fiscal years. We adopted ASU 2018-07 on January 1, 2019, and the adoption did not have a material impact on our consolidated financial statements. In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which requires more timely recognition of credit losses associated with financial assets. This update is effective for fiscal years beginning after December 15, 2019, and for interim periods within those fiscal years. Early adoption is permitted for fiscal years, and interim periods within those years, beginning after December 15, 2018. We are currently evaluating the impact, if any, that the adoption of ASU 2016-13 will have on our consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, Leases, which sets out the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e., lessees and lessors). ASU 2016-02 requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether the lease is effectively a financed purchase of the leased asset by the lessee. This classification will determine whether the lease expense is recognized based on an effective interest method or on a straight-line basis over the term of the lease. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months regardless of their classification. Leases with a term of 12 months or less will be accounted for similar to existing guidance for operating leases today. ASU 2016-02 supersedes previous leasing standards. For leases where we are the lessor, we account for these leases using an approach that is substantially equivalent to previous guidance prior to the adoption of ASU 2016-02. Additionally, under ASU 2016-02, lessors may only capitalize incremental direct leasing costs. For leases in which we are the lessee, we recognize a right-of-use asset and a lease liability equal to the present value of the minimum lease payments, with rent expense being recognized on a straight-line basis and the right of use asset being reduced when lease payments are made. In July 2018, the FASB issued ASU 2018-11 to provide entities with relief from the costs of implementing certain aspects of ASU 2016-02. The amendment to the new leases standard includes a practical expedient that provides lessors an option not to separate lease and non-lease components when certain criteria are met and instead account for those components as a single component under the new leases standard. The amendment also provides a transition option that permits the application of the new guidance as of the adoption date rather than to all periods presented. We elected the practical expedient to account for both our lease (primarily base rent) and non-lease (primarily tenant reimbursements) components as a single component under the leases standard and elected the new transition option. We adopted these pronouncements on January 1, 2019, and the adoption did not have a material impact on our consolidated financial statements, both as a lessor and as a lessee. Certain reclassifications were made to conform the prior period to our presentation of the condensed consolidated statements of operations as a result of adopting ASU 2016-02. Amounts that were previously disclosed as "Tenant reimbursements and other income" are now included in "Rental revenue" and are no longer presented as a separate line item. Parking revenues that do not represent components of leases and were previously disclosed as "Rental income" are now included in "Other revenue." Subsequent to January 1, 2019, provisions for credit losses are included in "Rental revenue." Provisions for credit losses prior to January 1, 2019 were disclosed as "Operating expenses" and were not reclassified to conform prior periods to the current presentation.

Summary of Significant Accounting Policies

Basis of Presentation

The accompanying condensed consolidated financial statements of EQC have been prepared without audit. Certain information and footnote disclosures required by U.S. generally accepted accounting principles, or GAAP, for complete financial statements have been condensed or omitted. We believe the disclosures made are appropriate. The accompanying condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes contained in our Annual Report on Form 10-K, or our Annual Report, for the year ended December 31, 2018. Capitalized terms used, but not defined in this Quarterly Report, have the same meanings as in our Annual Report.

In the opinion of our management, all adjustments, which include only normal recurring adjustments considered necessary for a fair presentation, have been included. All intercompany transactions and balances with or among our subsidiaries have been eliminated. Operating results for interim periods are not necessarily indicative of the results that may be expected for the full year. Certain reclassifications have been made to the prior year's financial statements to conform to the current year’s presentation.

The preparation of financial statements in conformity with GAAP requires us to make estimates and assumptions that affect reported amounts. Actual results could differ from those estimates. Significant estimates in the condensed consolidated financial statements include the assessment of the collectability of rental revenue, purchase price allocations, useful lives of fixed assets and impairment of real estate and intangible assets.

Share amounts are presented in whole numbers, except where noted.

Recent Accounting Pronouncements

In August 2018, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement, which changes the fair value measurement disclosure requirements of FASB Accounting Standards Codification, or ASC, 820. This update is effective for fiscal years beginning after December 15, 2019, and for interim periods within those fiscal years. We do not expect the adoption of ASU 2018-13 to have a material impact on our consolidated financial statements.

In June 2018, the FASB issued ASU 2018-07, Improvements to Nonemployee Share-Based Payment Accounting, which simplifies the accounting for share-based payments granted to nonemployees for goods and services. This update is effective for fiscal years beginning after December 15, 2018, and for interim periods within those fiscal years. We adopted ASU 2018-07 on January 1, 2019, and the adoption did not have a material impact on our consolidated financial statements.

In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which requires more timely recognition of credit losses associated with financial assets. This update is effective for fiscal years beginning after December 15, 2019, and for interim periods within those fiscal years. Early adoption is permitted for fiscal years, and interim periods within those years, beginning after December 15, 2018. We are currently evaluating the impact, if any, that the adoption of ASU 2016-13 will have on our consolidated financial statements.

In February 2016, the FASB issued ASU 2016-02, Leases, which sets out the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e., lessees and lessors). ASU 2016-02 requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether the lease is effectively a financed purchase of the leased asset by the lessee. This classification will determine whether the lease expense is recognized based on an effective interest method or on a straight-line basis over the term of the lease. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months regardless of their classification. Leases with a term of 12 months or less will be accounted for similar to existing guidance for operating leases today. ASU 2016-02 supersedes previous leasing standards. For leases where we are the lessor, we account for these leases using an approach that is substantially equivalent to previous guidance prior to the adoption of ASU 2016-02. Additionally, under ASU 2016-02, lessors may only capitalize incremental direct leasing costs. For leases in which we are the lessee, we recognize a right-of-use asset and a lease liability equal to the present value of the minimum lease payments, with rent expense being recognized on a straight-line basis and the right of use asset being reduced when lease payments are made.

In July 2018, the FASB issued ASU 2018-11 to provide entities with relief from the costs of implementing certain aspects of ASU 2016-02. The amendment to the new leases standard includes a practical expedient that provides lessors an option not to separate lease and non-lease components when certain criteria are met and instead account for those components as a single component under the new leases standard. The amendment also provides a transition option that permits the application of the new guidance as of the adoption date rather than to all periods presented. We elected the practical expedient to account for both our lease (primarily base rent) and non-lease (primarily tenant reimbursements) components as a single component under the leases standard and elected the new transition option. We adopted these pronouncements on January 1, 2019, and the adoption did not have a material impact on our consolidated financial statements, both as a lessor and as a lessee.

Certain reclassifications were made to conform the prior period to our presentation of the condensed consolidated statements of operations as a result of adopting ASU 2016-02. Amounts that were previously disclosed as "Tenant reimbursements and other income" are now included in "Rental revenue" and are no longer presented as a separate line item. Parking revenues that do not represent components of leases and were previously disclosed as "Rental income" are now included in "Other revenue." Subsequent to January 1, 2019, provisions for credit losses are included in "Rental revenue." Provisions for credit losses prior to January 1, 2019 were disclosed as "Operating expenses" and were not reclassified to conform prior periods to the current presentation.