Significant Accounting Policies (Policies)	9 Months Ended
Sep. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	The condensed consolidated financial statements are unaudited and include the accounts of AH4R, the Operating Partnership and their consolidated subsidiaries. The condensed consolidated financial statements of the Operating Partnership include the accounts of the Operating Partnership and its consolidated subsidiaries. Intercompany accounts and transactions have been eliminated. The Company consolidates real estate partnerships and other entities that are not variable interest entities (“VIEs”) when it owns, directly or indirectly, a majority interest in the entity or is otherwise able to control the entity. The Company consolidates VIEs in accordance with Accounting Standards Codification (“ASC”) No. 810, Consolidation, if it is the primary beneficiary of the VIE as determined by its power to direct the VIE’s activities and the obligation to absorb its losses or the right to receive its benefits, which are potentially significant to the VIE. Entities for which the Company owns an interest, but does not consolidate, are accounted for under the equity method of accounting as an investment in unconsolidated subsidiary and are included in escrow deposits, prepaid expenses and other assets within the condensed consolidated balance sheets. The ownership interest in a consolidated subsidiary of the Company held by outside parties, which was liquidated during the second quarter of 2018, is included in noncontrolling interest within the condensed consolidated financial statements. The condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and in conjunction with the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and footnote disclosures required for annual financial statements have been condensed or excluded pursuant to SEC rules and regulations. Accordingly, the condensed consolidated financial statements do not include all of the information and footnotes required by GAAP for complete financial statements and should be read in conjunction with the audited consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017. Any references in this report to the number of properties is outside the scope of our independent registered public accounting firm’s review of our financial statements, in accordance with the standards of the Public Company Accounting Oversight Board. In the opinion of management, all adjustments of a normal and recurring nature necessary for a fair presentation of the condensed consolidated financial statements for the interim periods have been made. The preparation of condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities and disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Recent Accounting Pronouncements	In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments, which is intended to reduce the existing diversity in practice by addressing eight specific cash flow issues related to how certain cash receipts and cash payments are presented and classified in the statement of cash flows. The guidance is effective for the Company for annual reporting periods beginning after December 15, 2017, and for interim periods within those annual periods with early adoption permitted. The Company adopted this guidance effective January 1, 2018. The adoption of this guidance did not have a material impact on our financial statements. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326), to amend the accounting for credit losses for certain financial instruments by requiring companies to recognize an estimate of expected credit losses as an allowance in order to recognize such losses more timely than under previous guidance that had allowed companies to wait until it was probable such losses had been incurred. The guidance will be effective for the Company for annual reporting periods beginning after December 15, 2019, and for interim periods within those annual periods. Early adoption is permitted for annual reporting periods beginning after December 15, 2018, and interim periods within those annual periods. The Company is currently assessing the impact of the guidance on our financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which sets forth principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e. lessors and lessees). Lessor accounting will remain similar to lessor accounting under previous guidance, while aligning with the FASB's new revenue recognition guidance for non-lease components. The new guidance will require lessees to recognize right-of-use assets and lease liabilities on the balance sheet for the rights and obligations created by all leases with terms of more than one year. The new guidance will also require lessees and lessors to capitalize, as initial direct costs, only those costs that are incurred due to the execution of a lease. Any other costs incurred, including allocated indirect costs, will no longer be capitalized and instead will be expensed as incurred. In July 2018, the FASB issued ASU No. 2018-11, Leases (Topic 842) Targeted Improvements, which provides lessors with a practical expedient, by class of underlying asset, to not separate non-lease components from the associated lease component if the non-lease components would otherwise be accounted for under the new revenue recognition standard and both the timing and pattern of transfer are the same for the non-lease components and associated lease component and, if accounted for separately, the lease component would be classified as an operating lease. As issued, ASU No. 2016-02 required modified retrospective application for all leases existing as of, or entered into after, the beginning of the earliest comparative period presented in the consolidated financial statements, with certain practical expedients available. ASU No. 2018-11 simplifies the transition requirements by providing companies an option to initially apply the new lease requirements as of the date of adoption and recognize a cumulative effect adjustment to the opening balance of retained earnings in the period of adoption. The Company will not need to restate comparative periods if it elects the simplified transition requirements provided by ASU No. 2018-11. The guidance will be effective for the Company for annual reporting periods beginning after December 15, 2018, and for interim periods within those annual periods, with early adoption permitted. The Company does not anticipate significant changes in the accounting for our residential operating leases for which we are the lessor, as our leases generally do not have terms of more than one year. We anticipate the adoption of this guidance will require us to recognize additional property management expenses for costs that were previously capitalizable as deferred leasing costs. As part of our operations, we lease office space for our corporate and property management offices under non-cancelable operating lease agreements for which we are the lessee. We anticipate that the adoption of this guidance will require us to recognize a right-of-use asset and corresponding lease liability for these office leases. The Company is currently assessing the impact of the adoption of this guidance on our policies, internal controls and financial statements. In January 2016, the FASB issued ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities, which amends certain aspects of recognition, measurement, presentation and disclosure of financial instruments, including the requirement to measure certain equity investments at fair value with changes in fair value recognized in net income. The guidance is effective for the Company for annual reporting periods beginning after December 15, 2017, and for interim periods within those annual periods. The Company adopted this guidance effective January 1, 2018. The adoption of this guidance did not have a material impact on our financial statements. In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which provides guidance on revenue recognition and supersedes the revenue recognition requirements in Topic 605, Revenue Recognition, most industry-specific guidance and some cost guidance included in Subtopic 605-35, “Revenue Recognition-Construction-Type and Production-Type Contracts.” The standard’s core principle is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. In doing so, companies will need to use more judgment and make more estimates than under current guidance. These judgments include identifying “distinct” performance obligations in multi-element contracts, estimating the amount of variable consideration to include in the transaction price at contract inception, allocating the transaction price to each separate performance obligation, and determining at contract inception whether the performance obligation is satisfied over time or at a point in time. Since lease contracts under ASC 840, "Leases", are specifically excluded from ASU No. 2014-09’s scope, most of the Company’s rental contract revenue will continue to follow current leasing guidance. We have reviewed our other sources of revenue and identified that the non-lease components (tenant chargebacks and recovery revenue) in our single-family home and office leases will continue being accounted for under ASC 840 until the adoption of ASU 2016-02 beginning January 1, 2019. Based on our assessment, the Company’s current accounting policies for these non-lease components are aligned with the revenue recognition principles prescribed by the new guidance. Therefore, the new standard did not ultimately change the amount or timing of our revenue recognition. As part of ASU No. 2014-09, the FASB issued consequential amendments to other sections, eliminating ASC 360-20, Real Estate Sales and adding ASU No. 2017-05 Other Income-Gains and Losses from the Derecognition of Nonfinancial Assets, Subtopic 610-20, "Other Income". Real estate sales to noncustomers will follow new guidance from ASC 610-20, while sales to customers will follow the general revenue guidance in ASC 606. While the Company’s property sales are not part of our ordinary customer activity and will fall under ASC 610-20, there is little economic difference in the accounting for real estate sales to customers versus noncustomers, with the exception of the presentation of comprehensive income (revenue and expense when sales to customers or gains and losses when sales to noncustomers). The Company adopted the new revenue recognition guidance using the modified retrospective approach, effective January 1, 2018. We evaluated the revenue recognition for our contracts under existing accounting standards and under the new revenue recognition ASU and determined that there were no differences in the amounts or timing of recognition. Therefore, the adoption of this ASU did not result in an adjustment to our retained earnings on January 1, 2018. In February 2018, the FASB issued ASU No. 2018-03, Recognition and Measurement of Financial Assets and Financial Liabilities, which retained the current framework for accounting for financial instruments in GAAP but made targeted improvements to address certain aspects of recognition, measurement, presentation, and disclosure of financial instruments. The guidance is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years beginning after June 15, 2018. The Company adopted this guidance effective July 1, 2018. The adoption of this guidance did not have a material impact on our financial statements. In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820) Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement, which eliminates, adds and modifies certain disclosure requirements for fair value measurements. Companies will no longer be required to disclose the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy. Companies will also be required to disclose the range and weighted average used to develop significant unobservable inputs for Level 3 fair value measurements. The guidance is effective for fiscal years beginning after December 15, 2019, and for interim periods within those annual periods with early adoption permitted. The Company is currently assessing the impact of the guidance on our financial statements. In August 2018, the FASB issued ASU No. 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40) Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract, which aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal use software license). Capitalized implementation costs related to a hosting arrangement that is a service contract will be amortized over the term of the hosting arrangement, beginning when the module or component of the hosting arrangement is ready for its intended use. The guidance is effective for fiscal years beginning after December 15, 2019, and for interim periods within those annual periods with early adoption permitted. The Company is currently assessing the impact of the guidance on our financial statements.

In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments, which is intended to reduce the existing diversity in practice by addressing eight specific cash flow issues related to how certain cash receipts and cash payments are presented and classified in the statement of cash flows. The guidance is effective for the Company for annual reporting periods beginning after December 15, 2017, and for interim periods within those annual periods with early adoption permitted. The Company adopted this guidance effective January 1, 2018. The adoption of this guidance did not have a material impact on our financial statements.

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326), to amend the accounting for credit losses for certain financial instruments by requiring companies to recognize an estimate of expected credit losses as an allowance in order to recognize such losses more timely than under previous guidance that had allowed companies to wait until it was probable such losses had been incurred. The guidance will be effective for the Company for annual reporting periods beginning after December 15, 2019, and for interim periods within those annual periods. Early adoption is permitted for annual reporting periods beginning after December 15, 2018, and interim periods within those annual periods. The Company is currently assessing the impact of the guidance on our financial statements.

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which sets forth principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e. lessors and lessees). Lessor accounting will remain similar to lessor accounting under previous guidance, while aligning with the FASB's new revenue recognition guidance for non-lease components. The new guidance will require lessees to recognize right-of-use assets and lease liabilities on the balance sheet for the rights and obligations created by all leases with terms of more than one year. The new guidance will also require lessees and lessors to capitalize, as initial direct costs, only those costs that are incurred due to the execution of a lease. Any other costs incurred, including allocated indirect costs, will no longer be capitalized and instead will be expensed as incurred. In July 2018, the FASB issued ASU No. 2018-11, Leases (Topic 842) Targeted Improvements, which provides lessors with a practical expedient, by class of underlying asset, to not separate non-lease components from the associated lease component if the non-lease components would otherwise be accounted for under the new revenue recognition standard and both the timing and pattern of transfer are the same for the non-lease components and associated lease component and, if accounted for separately, the lease component would be classified as an operating lease. As issued, ASU No. 2016-02 required modified retrospective application for all leases existing as of, or entered into after, the beginning of the earliest comparative period presented in the consolidated financial statements, with certain practical expedients available. ASU No. 2018-11 simplifies the transition requirements by providing companies an option to initially apply the new lease requirements as of the date of adoption and recognize a cumulative effect adjustment to the opening balance of retained earnings in the period of adoption. The Company will not need to restate comparative periods if it elects the simplified transition requirements provided by ASU No. 2018-11.

The guidance will be effective for the Company for annual reporting periods beginning after December 15, 2018, and for interim periods within those annual periods, with early adoption permitted. The Company does not anticipate significant changes in the accounting for our residential operating leases for which we are the lessor, as our leases generally do not have terms of more than one year. We anticipate the adoption of this guidance will require us to recognize additional property management expenses for costs that were previously capitalizable as deferred leasing costs. As part of our operations, we lease office space for our corporate and property management offices under non-cancelable operating lease agreements for which we are the lessee. We anticipate that the adoption of this guidance will require us to recognize a right-of-use asset and corresponding lease liability for these office leases. The Company is currently assessing the impact of the adoption of this guidance on our policies, internal controls and financial statements.

In January 2016, the FASB issued ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities, which amends certain aspects of recognition, measurement, presentation and disclosure of financial instruments, including the requirement to measure certain equity investments at fair value with changes in fair value recognized in net income. The guidance is effective for the Company for annual reporting periods beginning after December 15, 2017, and for interim periods within those annual periods. The Company adopted this guidance effective January 1, 2018. The adoption of this guidance did not have a material impact on our financial statements.

In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which provides guidance on revenue recognition and supersedes the revenue recognition requirements in Topic 605, Revenue Recognition, most industry-specific guidance and some cost guidance included in Subtopic 605-35, “Revenue Recognition-Construction-Type and Production-Type Contracts.” The standard’s core principle is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. In doing so, companies will need to use more judgment and make more estimates than under current guidance. These judgments include identifying “distinct” performance obligations in multi-element contracts, estimating the amount of variable consideration to include in the transaction price at contract inception, allocating the transaction price to each separate performance obligation, and determining at contract inception whether the performance obligation is satisfied over time or at a point in time. Since lease contracts under ASC 840, "Leases", are specifically excluded from ASU No. 2014-09’s scope, most of the Company’s rental contract revenue will continue to follow current leasing guidance. We have reviewed our other sources of revenue and identified that the non-lease components (tenant chargebacks and recovery revenue) in our single-family home and office leases will continue being accounted for under ASC 840 until the adoption of ASU 2016-02 beginning January 1, 2019. Based on our assessment, the Company’s current accounting policies for these non-lease components are aligned with the revenue recognition principles prescribed by the new guidance. Therefore, the new standard did not ultimately change the amount or timing of our revenue recognition. As part of ASU No. 2014-09, the FASB issued consequential amendments to other sections, eliminating ASC 360-20, Real Estate Sales and adding ASU No. 2017-05 Other Income-Gains and Losses from the Derecognition of Nonfinancial Assets, Subtopic 610-20, "Other Income". Real estate sales to noncustomers will follow new guidance from ASC 610-20, while sales to customers will follow the general revenue guidance in ASC 606. While the Company’s property sales are not part of our ordinary customer activity and will fall under ASC 610-20, there is little economic difference in the accounting for real estate sales to customers versus noncustomers, with the exception of the presentation of comprehensive income (revenue and expense when sales to customers or gains and losses when sales to noncustomers). The Company adopted the new revenue recognition guidance using the modified retrospective approach, effective January 1, 2018. We evaluated the revenue recognition for our contracts under existing accounting standards and under the new revenue recognition ASU and determined that there were no differences in the amounts or timing of recognition. Therefore, the adoption of this ASU did not result in an adjustment to our retained earnings on January 1, 2018.

In February 2018, the FASB issued ASU No. 2018-03, Recognition and Measurement of Financial Assets and Financial Liabilities, which retained the current framework for accounting for financial instruments in GAAP but made targeted improvements to address certain aspects of recognition, measurement, presentation, and disclosure of financial instruments. The guidance is effective for fiscal years beginning after December 15, 2017, and interim periods within those fiscal years beginning after June 15, 2018. The Company adopted this guidance effective July 1, 2018. The adoption of this guidance did not have a material impact on our financial statements.

In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement (Topic 820) Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement, which eliminates, adds and modifies certain disclosure requirements for fair value measurements. Companies will no longer be required to disclose the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy. Companies will also be required to disclose the range and weighted average used to develop significant unobservable inputs for Level 3 fair value measurements. The guidance is effective for fiscal years beginning after December 15, 2019, and for interim periods within those annual periods with early adoption permitted. The Company is currently assessing the impact of the guidance on our financial statements.

In August 2018, the FASB issued ASU No. 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40) Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract, which aligns the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal use software license). Capitalized implementation costs related to a hosting arrangement that is a service contract will be amortized over the term of the hosting arrangement, beginning when the module or component of the hosting arrangement is ready for its intended use. The guidance is effective for fiscal years beginning after December 15, 2019, and for interim periods within those annual periods with early adoption permitted. The Company is currently assessing the impact of the guidance on our financial statements.