Basis of Presentation, Principles of Consolidation, and Use of Estimates	3 Months Ended
Mar. 31, 2017
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Basis of Presentation, Principles of Consolidation, and Use of Estimates	1. Basis of Presentation, Principles of Consolidation, and Use of Estimates Basis of Presentation The accompanying condensed consolidated financial statements have been prepared by Alliance HealthCare Services, Inc. (the “Company” or “Alliance”) in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and with the instructions to Form 10-Q and Article 10 of Regulation S-X of the Securities and Exchange Commission. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments (including normal recurring accruals) considered necessary for a fair presentation have been included. Operating results for the three months ended March 31, 2017 are not necessarily indicative of the results that may be expected for the year ending December 31, 2017. The accompanying condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes to the consolidated financial statements for the year ended December 31, 2016. For a complete summary of the Company’s significant accounting policies, refer to Note 2, “Summary of Significant Accounting Policies,” in Part IV, Item 15 of the Company’s 2016 Form 10-K, filed with the SEC on March 10, 2017. There have been no material changes to the Company’s significant accounting policies during the three months ended March 31, 2017. Pending Transaction On April 10, 2017, the Company entered into an agreement and plan of merger (the “Merger Agreement”) by and among Tahoe Investment Group Co., Ltd., an entity organized under the laws of the People’s Republic of China (“Tahoe”), THAIHOT Investment Company Limited, an exempted company incorporated under the laws of the Cayman Islands and indirect wholly-owned subsidiary of Tahoe (“THAIHOT”), THAIHOT Investment Company US Limited, a Delaware corporation and indirect wholly-owned subsidiary of Tahoe (“Parent”) and Alliance Healthcare Services Merger Sub Limited, a Delaware corporation and wholly-owned subsidiary of Parent (“Sub” and together with Tahoe, THAIHOT and Parent, the “Purchaser Parties”) providing for the merger of Sub with and into Alliance (the “Merger”), with Alliance surviving the Merger as a wholly-owned subsidiary of Parent. Under the Merger Agreement, the Purchaser Parties will acquire all of the Company’s outstanding common stock that is not beneficially owned by the Purchaser Parties or owned by the Company as treasury shares. The Merger is subject to approval by Alliance’s stockholders, including a non-waiveable condition requiring approval by the holders of a majority of the outstanding shares of Alliance common stock that are not beneficially owned by the Purchaser Parties or certain senior executive officers of the Company, as well as certain other customary closing conditions. The Merger is not subject to a financing condition. The Company will call a meeting of stockholders for the purpose of voting on the adoption of the Merger Agreement in due course. If completed, the Merger will result in the Company becoming a privately held company and Alliance’s common stock would no longer be listed on NASDAQ. See Note 17 for details. Principles of Consolidation The accompanying condensed consolidated financial statements of the Company include the assets, liabilities, revenues and expenses of all subsidiaries over which the Company exercises control. Intercompany transactions have been eliminated. The Company evaluates participating rights in its assessment of control in determining consolidation of joint venture partners. The Company records noncontrolling interest related to its consolidated subsidiaries that are not wholly-owned. Investments in unconsolidated investees over which it exercises significant influence but does not control are accounted for under the equity method. Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. Actual results could differ from those estimates.

1. Basis of Presentation, Principles of Consolidation, and Use of Estimates

Basis of Presentation The accompanying condensed consolidated financial statements have been prepared by Alliance HealthCare Services, Inc. (the “Company” or “Alliance”) in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and with the instructions to Form 10-Q and Article 10 of Regulation S-X of the Securities and Exchange Commission. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments (including normal recurring accruals) considered necessary for a fair presentation have been included. Operating results for the three months ended March 31, 2017 are not necessarily indicative of the results that may be expected for the year ending December 31, 2017. The accompanying condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes to the consolidated financial statements for the year ended December 31, 2016.

For a complete summary of the Company’s significant accounting policies, refer to Note 2, “Summary of Significant Accounting Policies,” in Part IV, Item 15 of the Company’s 2016 Form 10-K, filed with the SEC on March 10, 2017. There have been no material changes to the Company’s significant accounting policies during the three months ended March 31, 2017.

Pending Transaction On April 10, 2017, the Company entered into an agreement and plan of merger (the “Merger Agreement”) by and among Tahoe Investment Group Co., Ltd., an entity organized under the laws of the People’s Republic of China (“Tahoe”), THAIHOT Investment Company Limited, an exempted company incorporated under the laws of the Cayman Islands and indirect wholly-owned subsidiary of Tahoe (“THAIHOT”), THAIHOT Investment Company US Limited, a Delaware corporation and indirect wholly-owned subsidiary of Tahoe (“Parent”) and Alliance Healthcare Services Merger Sub Limited, a Delaware corporation and wholly-owned subsidiary of Parent (“Sub” and together with Tahoe, THAIHOT and Parent, the “Purchaser Parties”) providing for the merger of Sub with and into Alliance (the “Merger”), with Alliance surviving the Merger as a wholly-owned subsidiary of Parent. Under the Merger Agreement, the Purchaser Parties will acquire all of the Company’s outstanding common stock that is not beneficially owned by the Purchaser Parties or owned by the Company as treasury shares. The Merger is subject to approval by Alliance’s stockholders, including a non-waiveable condition requiring approval by the holders of a majority of the outstanding shares of Alliance common stock that are not beneficially owned by the Purchaser Parties or certain senior executive officers of the Company, as well as certain other customary closing conditions. The Merger is not subject to a financing condition. The Company will call a meeting of stockholders for the purpose of voting on the adoption of the Merger Agreement in due course. If completed, the Merger will result in the Company becoming a privately held company and Alliance’s common stock would no longer be listed on NASDAQ. See Note 17 for details.

Principles of Consolidation The accompanying condensed consolidated financial statements of the Company include the assets, liabilities, revenues and expenses of all subsidiaries over which the Company exercises control. Intercompany transactions have been eliminated. The Company evaluates participating rights in its assessment of control in determining consolidation of joint venture partners. The Company records noncontrolling interest related to its consolidated subsidiaries that are not wholly-owned. Investments in unconsolidated investees over which it exercises significant influence but does not control are accounted for under the equity method.

Use of Estimates The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. Actual results could differ from those estimates.