Accounting Standards Update	12 Months Ended
Dec. 31, 2017
Accounting Policies [Abstract]
New Accounting Pronouncements, Policy [Policy Text Block]	Accounting Standards Update Recently Adopted Accounting Pronouncements Effective January 1, 2017, the Company adopted Accounting Standards Update ("ASU") No. 2016-09, Compensation - Stock Compensation (Topic 718). Under this standard, excess tax benefits and deficiencies are recognized as income tax benefit or expense in the consolidated statement of operations and comprehensive income, rather than in the consolidated balance sheet within additional paid-in capital. This change in accounting for excess tax benefits and deficiencies is applied prospectively to the consolidated statements of operations and comprehensive income. The Company elected to present retrospectively its gross excess tax benefits as cash flows from operating activities in the consolidated statements of cash flows. The adoption of ASU 2016-09 did not have an impact on the opening balance of retained earnings. The Company elected to continue to estimate expected forfeitures to determine the amount of stock-based compensation expense to be recognized. During 2017, the Company recognized net excess tax benefits of $4.5 million ($0.09 per diluted share), which reduced the provision for income taxes and increased income from continuing operations and net income. In the years ended December 31, 2016 and 2015, the Company reclassified $3.1 million and $6.6 million, respectively, gross excess tax benefits related to stock-based compensation out of cash flows from financing activities and into cash flows from operating activities. Effective December 31, 2017, the Company adopted ASU No. 2016-18, Statement of Cash Flows (Topic 230). This standard prescribes amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning and end-of-period total amounts shown on the statement of cash flows. Prior to this standard there was no specific guidance on the cash flow classification and presentation of changes in restricted cash or restricted cash equivalents. This standard should be applied using a retrospective transition method for each period presented. The adoption of this standard did not have a significant impact on the Company’s financial statements. Accounting Pronouncements Not Yet Adopted In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which outlines a comprehensive new revenue recognition model designed to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The new standard also requires additional quantitative and qualitative disclosures. The Company has completed its analysis and adopted the new standard effective January 1, 2018 using the modified retrospective method. The modified retrospective method requires entities to apply the new revenue standard only to the current-year in which the standard is first implemented. Upon adoption, the Company did not have an opening retained earnings adjustment. The Company will change its presentation of the allowance for fallouts (permanent placement candidates that do not remain with the client through the contingency period, which is typically 90 days or less) on its consolidated balance sheets, which is currently included in accounts receivable allowances and the balance is $1.5 million as of December 31, 2017; under the new standard these are considered contract liabilities and upon adoption of the standard they will be presented as liabilities on the Company’s consolidated balance sheet. Aside from this change, the adoption of this standard is not expected to have a material impact on its consolidated financial statements and disclosures. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which is intended to improve financial reporting about leasing transactions. This standard requires a lessee to record on the balance sheet the assets and liabilities for the rights and obligations created by lease terms of more than 12 months. The Company is required to adopt this standard effective January 1, 2019. The Company commenced its assessment of the new standard during the fourth quarter of 2017, developed a project plan to guide the implementation and is evaluating the impact the new standard will have on its consolidated financial statements. In January 2017, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2017-01, Business Combinations (Topic 805) Clarifying the Definition of a Business. The amendments in this update clarify the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions or disposals of assets or businesses. The definition of a business affects many areas of accounting including acquisitions, disposals, goodwill and consolidation. The Company adopted this standard on January 1, 2018 and its application did not have a material impact on its consolidated financial statements. In January 2017, the FASB issued ASU No. 2017-04, Intangibles-Goodwill and Other (Topic 350) Simplifying the Test for Goodwill Impairment. The new guidance eliminates Step 2 of the goodwill impairment test which requires companies to calculate the implied fair value of goodwill, determined in the same manner as the amount of goodwill recognized in a business combination and using a hypothetical purchase price allocation. Under the new guidance, goodwill impairment will now be measured as the amount by which a reporting unit’s carrying value exceeds its fair value. The Company is required to adopt this standard on January 1, 2020, and early adoption is permitted. The Company does not expect the adoption of this guidance will have a material impact on its consolidated financial statements. In May 2017, the FASB issued ASU No. 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting. This ASU provides guidance on the types of changes to the terms or conditions of share-based payment awards to which an entity would be required to apply modification accounting. An entity would not apply modification accounting if the fair value, vesting conditions and classification of the awards are the same immediately before and after the modification. The amendments in this ASU will be applied prospectively to awards modified on or after the adoption date. The Company adopted this standard on January 1, 2018 and its application did not have a material impact on its consolidated financial statements.

Accounting Standards Update

Recently Adopted Accounting Pronouncements

Effective January 1, 2017, the Company adopted Accounting Standards Update ("ASU") No. 2016-09, Compensation - Stock Compensation (Topic 718). Under this standard, excess tax benefits and deficiencies are recognized as income tax benefit or expense in the consolidated statement of operations and comprehensive income, rather than in the consolidated balance sheet within additional paid-in capital. This change in accounting for excess tax benefits and deficiencies is applied prospectively to the consolidated statements of operations and comprehensive income. The Company elected to present retrospectively its gross excess tax benefits as cash flows from operating activities in the consolidated statements of cash flows. The adoption of ASU 2016-09 did not have an impact on the opening balance of retained earnings. The Company elected to continue to estimate expected forfeitures to determine the amount of stock-based compensation expense to be recognized. During 2017, the Company recognized net excess tax benefits of $4.5 million ($0.09 per diluted share), which reduced the provision for income taxes and increased income from continuing operations and net income. In the years ended December 31, 2016 and 2015, the Company reclassified $3.1 million and $6.6 million, respectively, gross excess tax benefits related to stock-based compensation out of cash flows from financing activities and into cash flows from operating activities.

Effective December 31, 2017, the Company adopted ASU No. 2016-18, Statement of Cash Flows (Topic 230). This standard prescribes amounts generally described as restricted cash and restricted cash equivalents should be included with cash and cash equivalents when reconciling the beginning and end-of-period total amounts shown on the statement of cash flows. Prior to this standard there was no specific guidance on the cash flow classification and presentation of changes in restricted cash or restricted cash equivalents. This standard should be applied using a retrospective transition method for each period presented. The adoption of this standard did not have a significant impact on the Company’s financial statements.

Accounting Pronouncements Not Yet Adopted

In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), which outlines a comprehensive new revenue recognition model designed to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The new standard also requires additional quantitative and qualitative disclosures. The Company has completed its analysis and adopted the new standard effective January 1, 2018 using the modified retrospective method. The modified retrospective method requires entities to apply the new revenue standard only to the current-year in which the standard is first implemented. Upon adoption, the Company did not have an opening retained earnings adjustment. The Company will change its presentation of the allowance for fallouts (permanent placement candidates that do not remain with the client through the contingency period, which is typically 90 days or less) on its consolidated balance sheets, which is currently included in accounts receivable allowances and the balance is $1.5 million as of December 31, 2017; under the new standard these are considered contract liabilities and upon adoption of the standard they will be presented as liabilities on the Company’s consolidated balance sheet. Aside from this change, the adoption of this standard is not expected to have a material impact on its consolidated financial statements and disclosures.

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which is intended to improve financial reporting about leasing transactions. This standard requires a lessee to record on the balance sheet the assets and liabilities for the rights and obligations created by lease terms of more than 12 months. The Company is required to adopt this standard effective January 1, 2019. The Company commenced its assessment of the new standard during the fourth quarter of 2017, developed a project plan to guide the implementation and is evaluating the impact the new standard will have on its consolidated financial statements.

In January 2017, the Financial Accounting Standards Board (“FASB”) issued ASU No. 2017-01, Business Combinations (Topic 805) Clarifying the Definition of a Business. The amendments in this update clarify the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions or disposals of assets or businesses. The definition of a business affects many areas of accounting including acquisitions, disposals, goodwill and consolidation. The Company adopted this standard on January 1, 2018 and its application did not have a material impact on its consolidated financial statements.

In January 2017, the FASB issued ASU No. 2017-04, Intangibles-Goodwill and Other (Topic 350) Simplifying the Test for Goodwill Impairment. The new guidance eliminates Step 2 of the goodwill impairment test which requires companies to calculate the implied fair value of goodwill, determined in the same manner as the amount of goodwill recognized in a business combination and using a hypothetical purchase price allocation. Under the new guidance, goodwill impairment will now be measured as the amount by which a reporting unit’s carrying value exceeds its fair value. The Company is required to adopt this standard on January 1, 2020, and early adoption is permitted. The Company does not expect the adoption of this guidance will have a material impact on its consolidated financial statements.

In May 2017, the FASB issued ASU No. 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting. This ASU provides guidance on the types of changes to the terms or conditions of share-based payment awards to which an entity would be required to apply modification accounting. An entity would not apply modification accounting if the fair value, vesting conditions and classification of the awards are the same immediately before and after the modification. The amendments in this ASU will be applied prospectively to awards modified on or after the adoption date. The Company adopted this standard on January 1, 2018 and its application did not have a material impact on its consolidated financial statements.