Revenues (Notes)	3 Months Ended
Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenues	3. Revenues Adoption of ASC Topic 606, Revenue from Contracts with Customers ("ASC 606") Effective January 1, 2018, the Company adopted ASC 606 using the modified retrospective method, which allows companies to apply the new revenue standard to reporting periods beginning in the year the standard is first implemented, while prior periods continue to be reported in accordance with previous accounting guidance. Since the adoption of ASC 606 did not have a significant impact on the recognition of revenues, the Company did not have an opening retained earnings adjustment. Revenue Recognition Revenues are recognized as control of the promised service is transferred to customers, in an amount that reflects the consideration expected in exchange for the services. Revenues from contract assignments are recognized over time, based on hours worked by the Company’s contract professionals. The performance of the requested service over time is the single performance obligation for assignment revenues. Certain customers may receive discounts (e.g., volume discounts, rebates, prompt-pay discounts) and adjustments to the amounts billed. These discounts, rebates and adjustments are considered variable consideration. Volume discounts are the largest component of variable consideration and are estimated using the most likely amount method prescribed by ASC 606, contracts terms and estimates of revenue. Revenues are recognized net of variable consideration to the extent that it is probable that a significant reversal of revenues will not occur in subsequent periods. Payment terms vary and the time between invoicing and when payment is due is not significant. There are no financing components to the Company’s arrangements. There are no incremental costs to obtain contracts and costs to fulfill contracts are expensed as incurred. The Company recognizes revenues on a gross basis as it acts as a principal in its transactions. The Company has direct contractual relationships with its customers, bears the risks and rewards of its arrangements, has the discretion to select the contract professionals and establish the price for the services to be provided. Additionally, the Company retains control over its contract professionals based on its contractual arrangements. The Company primarily provides services through its employees and to a lesser extent, through subcontractors; the related costs are included in costs of services. The Company includes billable expenses (out-of-pocket reimbursable expenses) in revenues and the associated expenses are included in costs of services. Permanent placement revenues are recognized at a point in time when employment candidates begin permanent employment. Finding a qualified candidate that the client hires as a permanent employee is a single performance obligation for the Company’s permanent placement contracts. Revenues recognized from permanent placement services are based upon a percentage of the candidates' base salary. The Company records a liability for permanent placement candidates that do not remain with the client through the contingency period, which is typically 90 days or less ("fallouts"). When a fallout occurs the Company will generally find a replacement candidate at no additional cost to the client. Prior to the adoption of ASC 606, the estimate for permanent placement fallouts was recorded as accounts receivable allowances and effective January 1, 2018 this estimate is considered a contract liability and was $1.5 million. See "Note 11. Segment Reporting," for assignment revenues and permanent placement revenues by segment. Accounts Receivable Allowances The Company estimates its credit losses (the inability of customers to make required payments) based on (i) a combination of past experience and current trends, (ii) consideration of the current aging of receivables and (iii) a specific review for potential bad debts. The resulting bad debt expense is included in selling, general and administrative ("SG&A") expenses. The allowance was $4.9 million at March 31, 2018 and $9.9 million at December 31, 2017. The December 31, 2017 allowance included estimates of $3.1 million for fallouts and other revenue adjustments, which prior to the adoption of ASC 606 were presented in the balance sheet as accounts receivable allowances. The presentation of these items in the condensed consolidated statement of cash flows for the current period have been conformed to their presentation in the balance sheet.

3. Revenues

Adoption of ASC Topic 606, Revenue from Contracts with Customers ("ASC 606")

Effective January 1, 2018, the Company adopted ASC 606 using the modified retrospective method, which allows companies to apply the new revenue standard to reporting periods beginning in the year the standard is first implemented, while prior periods continue to be reported in accordance with previous accounting guidance. Since the adoption of ASC 606 did not have a significant impact on the recognition of revenues, the Company did not have an opening retained earnings adjustment.

Revenue Recognition

Revenues are recognized as control of the promised service is transferred to customers, in an amount that reflects the consideration expected in exchange for the services. Revenues from contract assignments are recognized over time, based on hours worked by the Company’s contract professionals. The performance of the requested service over time is the single performance obligation for assignment revenues. Certain customers may receive discounts (e.g., volume discounts, rebates, prompt-pay discounts) and adjustments to the amounts billed. These discounts, rebates and adjustments are considered variable consideration. Volume discounts are the largest component of variable consideration and are estimated using the most likely amount method prescribed by ASC 606, contracts terms and estimates of revenue. Revenues are recognized net of variable consideration to the extent that it is probable that a significant reversal of revenues will not occur in subsequent periods. Payment terms vary and the time between invoicing and when payment is due is not significant. There are no financing components to the Company’s arrangements. There are no incremental costs to obtain contracts and costs to fulfill contracts are expensed as incurred.

The Company recognizes revenues on a gross basis as it acts as a principal in its transactions. The Company has direct contractual relationships with its customers, bears the risks and rewards of its arrangements, has the discretion to select the contract professionals and establish the price for the services to be provided. Additionally, the Company retains control over its contract professionals based on its contractual arrangements. The Company primarily provides services through its employees and to a lesser extent, through subcontractors; the related costs are included in costs of services. The Company includes billable expenses (out-of-pocket reimbursable expenses) in revenues and the associated expenses are included in costs of services.

Permanent placement revenues are recognized at a point in time when employment candidates begin permanent employment. Finding a qualified candidate that the client hires as a permanent employee is a single performance obligation for the Company’s permanent placement contracts. Revenues recognized from permanent placement services are based upon a percentage of the candidates' base salary. The Company records a liability for permanent placement candidates that do not remain with the client through the contingency period, which is typically 90 days or less ("fallouts"). When a fallout occurs the Company will generally find a replacement candidate at no additional cost to the client. Prior to the adoption of ASC 606, the estimate for permanent placement fallouts was recorded as accounts receivable allowances and effective January 1, 2018 this estimate is considered a contract liability and was $1.5 million.

See "Note 11. Segment Reporting," for assignment revenues and permanent placement revenues by segment.

Accounts Receivable Allowances

The Company estimates its credit losses (the inability of customers to make required payments) based on (i) a combination of past experience and current trends, (ii) consideration of the current aging of receivables and (iii) a specific review for potential bad debts. The resulting bad debt expense is included in selling, general and administrative ("SG&A") expenses. The allowance was $4.9 million at March 31, 2018 and $9.9 million at December 31, 2017. The December 31, 2017 allowance included estimates of $3.1 million for fallouts and other revenue adjustments, which prior to the adoption of ASC 606 were presented in the balance sheet as accounts receivable allowances. The presentation of these items in the condensed consolidated statement of cash flows for the current period have been conformed to their presentation in the balance sheet.