Significant Accounting Policies	3 Months Ended
Mar. 31, 2019
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies 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, 2018. 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 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 remains similar to lessor accounting under previous guidance while aligning with the FASB's revised revenue recognition guidance for non-lease components of lease agreements. The new guidance requires 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 also requires lessees and lessors to capitalize, as initial direct costs, only those costs incurred due to the execution of a lease. Other costs previously capitalized under ASC 840, including indirect leasing costs, are 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. In December 2018, the FASB issued ASU No. 2018-20, Narrow-Scope Improvements for Lessors, which allows lessors to make an accounting policy election to exclude sales taxes and other similar taxes on lease transactions from lease revenue and the associated expense and requires lessors to exclude costs paid directly by lessees to third parties on the lessor’s behalf from lease revenue. The guidance is 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 adopted this guidance (the “new lease accounting standard”) effective January 1, 2019. As part of our accounting policy for the new guidance, the Company elected the simplified transition requirements provided by ASU No. 2018-11 and applied the new lease accounting standard beginning January 1, 2019. Comparative periods are not restated. We also elected the package of practical expedients which permits the Company to not reevaluate whether existing contracts contain leases, to not reevaluate existing leases for lease classification and to not reassess initial direct costs previously capitalized prior to the adoption of the new guidance. As a result of our accounting policy elections, the Company did not recognize a cumulative effect adjustment on January 1, 2019. The new guidance affects our policy for capitalizing initial direct costs. Had the Company adopted new guidance during the three months ended March 31, 2018, the Company would have expensed an additional $1.6 million of indirect leasing costs that were capitalized under the previous guidance. The Company classifies our single-family property leases as operating leases and elects to not separate the lease component, comprised of rents from single-family properties, from the associated non-lease component, comprised of fees from single-family properties and tenant charge-backs. The combined component is accounted for under the new lease accounting standard while certain tenant charge-backs are accounted for as variable payments under the revenue accounting guidance. As a result of the new guidance, the Company reclassified previously reported rents from single-family properties, fees from single-family properties and tenant charge-backs to rents and other single-family property revenues within the consolidated statements of operations. Beginning January 1, 2019, the Company also reclassified bad debt expense from property operating expenses to rents and other single-family property revenues within the consolidated statements of operations; previously reported property operating expenses were not restated. As a lessee, the Company recognized $4.8 million of lease liabilities and corresponding right-of-use assets on January 1, 2019, for office space we lease at our corporate headquarters in Agoura Hills, CA and at our field offices. In June 2018, the FASB issued ASU No. 2018-07, Compensation—Stock Compensation (Topic 718) Improvements to Nonemployee Share-Based Payment Accounting, which aligns the measurement and classification guidance for share-based payments to nonemployees with the guidance for share-based payments to employees, with certain exceptions. The guidance is effective for the Company in annual reporting periods beginning after December 15, 2018, and for interim periods within those annual periods. The Company adopted this guidance effective January 1, 2019. 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.

Significant Accounting Policies

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, 2018. 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 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 remains similar to lessor accounting under previous guidance while aligning with the FASB's revised revenue recognition guidance for non-lease components of lease agreements. The new guidance requires 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 also requires lessees and lessors to capitalize, as initial direct costs, only those costs incurred due to the execution of a lease. Other costs previously capitalized under ASC 840, including indirect leasing costs, are 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. In December 2018, the FASB issued ASU No. 2018-20, Narrow-Scope Improvements for Lessors, which allows lessors to make an accounting policy election to exclude sales taxes and other similar taxes on lease transactions from lease revenue and the associated expense and requires lessors to exclude costs paid directly by lessees to third parties on the lessor’s behalf from lease revenue. The guidance is 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 adopted this guidance (the “new lease accounting standard”) effective January 1, 2019. As part of our accounting policy for the new guidance, the Company elected the simplified transition requirements provided by ASU No. 2018-11 and applied the new lease accounting standard beginning January 1, 2019. Comparative periods are not restated. We also elected the package of practical expedients which permits the Company to not reevaluate whether existing contracts contain leases, to not reevaluate existing leases for lease classification and to not reassess initial direct costs previously capitalized prior to the adoption of the new guidance. As a result of our accounting policy elections, the Company did not recognize a cumulative effect adjustment on January 1, 2019. The new guidance affects our policy for capitalizing initial direct costs. Had the Company adopted new guidance during the three months ended March 31, 2018, the Company would have expensed an additional $1.6 million of indirect leasing costs that were capitalized under the previous guidance. The Company classifies our single-family property leases as operating leases and elects to not separate the lease component, comprised of rents from single-family properties, from the associated non-lease component, comprised of fees from single-family properties and tenant charge-backs. The combined component is accounted for under the new lease accounting standard while certain tenant charge-backs are accounted for as variable payments under the revenue accounting guidance. As a result of the new guidance, the Company reclassified previously reported rents from single-family properties, fees from single-family properties and tenant charge-backs to rents and other single-family property revenues within the consolidated statements of operations. Beginning January 1, 2019, the Company also reclassified bad debt expense from property operating expenses to rents and other single-family property revenues within the consolidated statements of operations; previously reported property operating expenses were not restated. As a lessee, the Company recognized $4.8 million of lease liabilities and corresponding right-of-use assets on January 1, 2019, for office space we lease at our corporate headquarters in Agoura Hills, CA and at our field offices.

In June 2018, the FASB issued ASU No. 2018-07, Compensation—Stock Compensation (Topic 718) Improvements to Nonemployee Share-Based Payment Accounting, which aligns the measurement and classification guidance for share-based payments to nonemployees with the guidance for share-based payments to employees, with certain exceptions. The guidance is effective for the Company in annual reporting periods beginning after December 15, 2018, and for interim periods within those annual periods. The Company adopted this guidance effective January 1, 2019. 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.