ASGN (ASGN) 10-Q 5 Nov 13 2013 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2013	Oct. 29, 2013
Entity Information [Line Items]	'	'
Entity Registrant Name	'ON ASSIGNMENT INC	'
Entity Central Index Key	'0000890564	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Accelerated Filer	'
Document Type	'10-Q	'
Document Period End Date	30-Sep-13	'
Document Fiscal Year Focus	'2013	'
Document Fiscal Period Focus	'Q3	'
Amendment Flag	'false	'
Entity Common Stock, Shares Outstanding	'	53,839,720

CONDENSED_CONSOLIDATED_BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Current Assets:	'	'
Cash and cash equivalents	$45,077	$27,479
Accounts receivable, net of allowance of $3,209 and $3,970, respectively	267,231	245,201
Prepaid expenses	7,454	8,839
Deferred income tax assets	10,083	10,147
Other	2,476	4,289
Total current assets	332,321	295,955
Property and equipment, net	33,481	26,862
Goodwill	496,553	496,158
Identifiable intangible assets, net	248,069	263,840
Other	8,058	15,206
Total Assets	1,118,482	1,098,021
Current Liabilities:	'	'
Current portion of long-term debt	10,000	10,000
Accounts payable	6,388	6,810
Accrued payroll and contract professional pay	75,094	59,962
Deferred compensation	5,150	10,000
Workers’ compensation and medical malpractice loss reserves	11,748	10,327
Income taxes payable	12,415	191
Current portion of accrued earn-outs	2,259	6,563
Other	16,011	14,874
Total current liabilities	139,065	118,727
Deferred income tax liabilities	22,963	23,009
Long-term debt	347,813	416,588
Other long-term liabilities	5,635	6,974
Total liabilities	515,476	565,298
Commitments and Contingencies	'	'
Stockholders’ Equity:	'	'
Preferred Stock, $0.01 par value, 1,000,000 shares authorized, no shares issued	0	0
Common Stock, $0.01 par value, 75,000,000 shares authorized, 53,823,353 and 52,960,570 issued and outstanding, respectively	538	530
Paid-in capital	489,064	471,711
Retained earnings	113,789	61,687
Accumulated other comprehensive loss	-385	-1,205
Total stockholders’ equity	603,006	532,723
Total Liabilities and Stockholders’ Equity	$1,118,482	$1,098,021

CONDENSED_CONSOLIDATED_BALANCE1

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, except Share data, unless otherwise specified
Current Assets:	'	'
Accounts receivable, allowance	$3,209	$3,970
Stockholders’ Equity:	'	'
Preferred Stock, par value (in dollars per share)	$0.01	$0.01
Preferred Stock, shares authorized (in shares)	1,000,000	1,000,000
Preferred Stock, shares issued (in shares)	0	0
Preferred Stock, shares outstanding (in shares)	0	0
Common Stock, par value (in dollars per share)	$0.01	$0.01
Common Stock, shares authorized (in shares)	75,000,000	75,000,000
Common Stock, shares issued (in shares)	53,823,354	52,960,570
Common Stock: shares outstanding (in shares)	53,823,354	52,960,570

CONDENSED_CONSOLIDATED_STATEME

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenues	$432,171	$374,511	$1,239,287	$797,134
Cost of services	301,555	258,880	870,830	544,217
Gross profit	130,616	115,631	368,457	252,917
Selling, general and administrative expenses	88,529	77,424	259,144	185,342
Amortization of intangible assets	5,199	6,679	15,853	11,197
Operating income	36,888	31,528	93,460	56,378
Interest expense, net	-3,257	-6,022	-12,786	-10,680
Write-off of loan costs	0	0	-14,958	-813
Income before income taxes	33,631	25,506	65,716	44,885
Provision for income taxes	13,422	10,850	27,075	19,105
Income from continuing operations	20,209	14,656	38,641	25,780
Gain on sale of discontinued operations, net of income taxes	0	0	14,412	0
Income (loss) from discontinued operations, net of income taxes	-59	847	-951	2,668
Basic earnings per common share:	'	'	'	'
Income from continuing operations	$0.38	$0.28	$0.72	$0.58
Income (loss) from discontinued operations	$0	$0.02	$0.26	$0.06
Net Income	$0.38	$0.30	$0.98	$0.64
Diluted earnings per common share:	'	'	'	'
Income from continuing operations	$0.37	$0.28	$0.71	$0.56
Income (loss) from discontinued operations	$0	$0.01	$0.25	$0.06
Net Income	$0.37	$0.29	$0.96	$0.62
Number of shares and share equivalents used to calculate earnings per share:	'	'	'	'
Basic	53,620	52,131	53,350	44,777
Diluted	54,624	53,162	54,394	45,807
Reconciliation of net income to comprehensive income:	'	'	'	'
Net income	20,150	15,503	52,102	28,448
Changes in fair value of derivatives, net of tax of $19 and $56 for the three months ended September 30, 2013 and 2012, respectively and $94 and $32 for the nine months ended September 30, 2013 and 2012, respectively	29	-93	172	-54
Foreign currency translation adjustment	1,504	776	648	106
Comprehensive income	$21,683	$16,186	$52,922	$28,500

CONDENSED_CONSOLIDATED_STATEME1

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (Parenthetical) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Changes in fair value of derivative, tax	$19	$56	$94	$32

CONDENSED_CONSOLIDATED_STATEME2

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Cash Flows from Operating Activities:	'	'
Net income	$52,102	$28,448
Adjustments to reconcile net income to net cash provided by operating activities:	'	'
Gain on sale of discontinued operations, net of income taxes	-14,412	0
Depreciation and amortization	21,658	16,023
Stock-based compensation	10,410	6,574
Write-off of loan costs	14,958	813
Gross excess tax benefits from stock-based compensation	-4,091	-2,713
Workers’ compensation and medical malpractice provision	5,119	2,827
Other	1,069	-412
Changes in operating assets and liabilities, net of effects of acquisitions and divestiture:	'	'
Accounts receivable	-33,992	-24,232
Prepaid expenses and income taxes	-3,655	-826
Accounts payable	-385	801
Accrued payroll and contract professional pay	19,927	-20,984
Deferred compensation	-4,850	-517
Other	2,780	7,185
Net cash provided by operating activities	73,948	14,639
Cash Flows from Investing Activities:	'	'
Cash paid for property and equipment	-12,293	-10,883
Cash received from sale of discontinued operations, net	31,922	0
Payments to Acquire Businesses, Net of Cash Acquired	0	-347,743
Other	-1,601	-1,885
Net cash provided by (used in) investing activities	18,028	-360,511
Cash Flows from Financing Activities:	'	'
Principal payments of long-term debt	-452,275	-160,663
Proceeds from Issuance of Long-term Debt	383,500	513,000
Proceeds from stock transactions	6,723	6,439
Payments of employment taxes related to release of restricted stock awards	-6,573	-2,312
Gross excess tax benefits from stock-based compensation	4,091	2,713
Debt issuance costs	-6,559	-17,103
Payments of accrued earn-outs	-3,425	0
Other	-14	-32
Net cash provided by financing activities	-74,532	342,042
Effect of exchange rate changes on cash and cash equivalents	154	-36
Net Increase in Cash and Cash Equivalents	17,598	-3,866
Cash and Cash Equivalents at Beginning of Year	27,479	17,739
Cash and Cash Equivalents at End of Period	45,077	13,873
Supplemental Disclosure of Cash Flow Information:	'	'
Income taxes	19,809	25,304
Interest	11,944	9,587
Supplemental Disclosure of Non-Cash Transactions:	'	'
Acquisition of property and equipment through accounts payable	981	745
Goodwill, Purchase Accounting Adjustments	0	-982
Stock Issued	$0	($225,558)

Financial_Statement_Presentati

Financial Statement Presentation	9 Months Ended
	Sep. 30, 2013
Organization, Consolidation and Presentation of Financial Statements [Abstract]	'
Financial Statement Presentation	'
	Financial Statement Presentation. The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America for interim financial information, the instructions to Form 10-Q and Regulation S-X. Accordingly, they do not include all of the information and footnotes required by accounting principles generally accepted in the United States of America for complete financial statements. The financial statements include adjustments consisting of normal recurring items, which, in the opinion of management, are necessary for a fair presentation of the financial position of On Assignment, Inc. and its subsidiaries (the "Company") and its results of operations for the interim dates and periods set forth herein. The results for the nine months ended September 30, 2013 are not necessarily indicative of the results to be expected for the full year or any other period. This Quarterly Report on Form 10-Q should be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2012, and with the Company's current report on Form 8-K filed on June 13, 2013.

Aquisitions

Aquisitions	9 Months Ended
	Sep. 30, 2013
Business Combinations [Abstract]	'
Acquisitions	'
	Acquisitions. On May 15, 2012, the Company acquired all of the outstanding shares of Apex Systems, Inc. ("Apex"), a privately-owned provider of information technology staffing services headquartered in Richmond, Virginia (the "Apex Acquisition"). The primary reason for the acquisition was to expand the Company's information technology staffing services. The purchase price totaled approximately $610.8 million, comprised of $385.3 million paid in cash and issuance of 14.3 million shares of common stock of the Company. Acquisition costs were approximately $9.8 million and were expensed in 2012. Goodwill is deductible for tax purposes. The results of operations of Apex have been combined with those of the Company since the acquisition date.
	Assets and liabilities of the acquired company were recorded at their estimated fair values at the date of acquisition. The excess purchase price over the fair value of net tangible assets and identifiable intangible assets acquired has been allocated to goodwill. The fair value assigned to identifiable intangible assets was determined primarily by using a discounted cash flow method.
	During the quarter ended June 30, 2013, the Company finalized the allocation of the purchase price upon resolution of a pre-acquisition contingency, resulting in a retrospective adjustment to the December 31, 2012 balance sheet to reflect a $2.2 million increase in accounts receivable and a corresponding decrease in goodwill.
	In the fourth quarter of 2012, the Company finalized the purchase price allocation and amortization method related to Apex's intangible assets. As required under the accounting guidance for business combinations, the accompanying condensed consolidated statements of operations for the three and nine months ended September 30, 2012 and the condensed consolidated statement of cash flows for the nine months ended September 30, 2012 , as well as the operating income by segment in Note 11, "Segment Reporting," have been restated to reflect the resulting additional amortization expense of $3.4 million ($1.9 million, net of taxes) for the three months ended September 30, 2012, and $5.0 million ($2.9 million, net of taxes) for the nine months ended September 30, 2012.
	The following table summarizes (in thousands) the final purchase price allocation for the acquisition of Apex:
	Current assets		$	172,042
	Property and equipment		902
	Goodwill		264,590
	Identifiable intangible assets		251,555
	Other		494
	Total assets acquired		$	689,583
	Current liabilities		$	77,905
	Other		850
	Total liabilities assumed		78,755
	Total purchase price		$	610,828
	The following table summarizes (in thousands) the allocation of the purchase price among the identifiable intangible assets for the acquisition of Apex:
		Useful life		Identifiable Intangible Asset Value
	Contractor relationships	5 years		$	10,589
	Customer relationships	10 years		92,147
	Non-compete agreements	7 years		2,076
	Trademarks	indefinite		146,743
	Total identifiable intangible assets acquired			$	251,555
	The summary below (in thousands, except for per share data) presents unaudited pro forma consolidated results of operations for the nine months ended September 30, 2012 as if the acquisition of Apex occurred on January 1, 2011. The pro forma financial information gives effect to certain adjustments, including: the amortization of intangible assets, interest expense on acquisition-related debt, and increased number of common shares as a result of the acquisition. Acquisition-related costs are assumed to have occurred at the beginning of the year prior to acquisition. The pro forma financial information is not necessarily indicative of the operating results that would have occurred if the acquisition had been consummated as of the date indicated, nor are they necessarily indicative of future operating results.
	Revenues	$	1,079,411
	Income from continuing operations	$	37,215
	Net income	$	39,883
	Basic earnings per share:
	Income from continuing operations	$	0.72
	Net income	$	0.77
	Diluted earnings per share:
	Income from continuing operations	$	0.7
	Net income	$	0.75
	Weighted average number of shares outstanding	51,929
	Weighted average number of shares and dilutive shares outstanding	52,959

Discontinued_Operations_Discon

Discontinued Operations Discontinued Operations	9 Months Ended
	Sep. 30, 2013
Discontinued Operations [Abstract]	'
Disposal Groups, Including Discontinued Operations, Disclosure [Text Block]	'
	Discontinued Operations. On February 12, 2013, the Company completed the sale of its Nurse Travel division for $33.7 million in cash and recognized a gain of $14.4 million, net of tax. The Nurse Travel division, previously included in the Healthcare segment, has been presented as discontinued operations in our Condensed Consolidated Statements of Operations for all periods presented. The following is a summary of the Nurse Travel division's operating results (in thousands):
		Three Months Ended					Nine Months Ended
		September 30,					September 30,
		2013			2012		2013			2012
	Revenues	$	—		$	13,772	$	6,408		$	40,912
	Income (loss) before income taxes	$	(119	)	$	1,347	$	(1,398	)	$	4,288
	Provision (benefit) for income taxes	$	(60	)	$	500	$	(447	)	$	1,620
	Net income (loss)	$	(59	)	$	847	$	(951	)	$	2,668

LongTerm_Debt

Long-Term Debt	9 Months Ended
	Sep. 30, 2013
Debt Disclosure [Abstract]	'
Long-Term Debt	'
	Long-Term Debt. Long-term debt consisted of the following (in thousands):
		September 30,			December 31, 2012
		2013
	Senior Secured Debt
	$125 million revolving credit facility, due May 2018	$	—		$	—
	$100 million term A loan facility, due May 2018	95,000			—
	$275 million term B loan facility, due May 2020	262,813			—
	$75 million revolving credit facility, repaid May 2013	—			—
	$100 million term A loan facility, repaid May 2013	—			92,500
	$365 million term B loan facility, repaid May 2013	—			334,088
		$	357,813		$	426,588
	At September 30, 2013, borrowings on the term A loan bore interest at 2.2 percent, and borrowings on the term B loan bore interest at 3.5 percent. The weighted average interest rate at September 30, 2013 was 3.2 percent.
	On May 16, 2013, the Company entered into a new $500.0 million credit facility and repaid all borrowing under the old facility. The new facility consists of (i) a $100.0 million, five-year term A loan facility, (ii) a $275.0 million seven-year term B loan facility and (iii) a $125.0 million, five-year revolving loan facility. Under terms of the new facility, the Company has the ability to increase the loan facilities for up to $100.0 million under certain specified conditions.
	Borrowings under the new facility bear interest at the Company's option, either the Eurodollar rate (LIBOR) or the base rate, plus 1.75% to 2.50% for the term A and revolving loans and LIBOR, with a floor of 1.0%, plus 2.50% for the term B loans. The commitment fee on the undrawn portion available under the revolving loan facility ranges from 0.25% to 0.40%.
	During the remainder of this fiscal year, each of the next four years and thereafter, the Company will be required to make payments as follows (in thousands):
	2013		$	2,500
	2014		10,000
	2015		10,000
	2016		10,000
	2017		10,875
	Thereafter		314,438
	Total		$	357,813
	The Company is also required to make mandatory prepayments of loans under the new facility, subject to specified exceptions, from excess cash flow and with the proceeds of asset sales, debt issuances and specified other events.
	The Company's obligations under the credit facility are guaranteed by substantially all of its direct and indirect domestic subsidiaries and secured by a lien on substantially all of the Company's tangible and intangible property and by a pledge of (i) all of the equity interests in its direct and indirect domestic subsidiaries and (ii) 65% of the equity interests in its first-tier foreign subsidiaries.
	In addition to other covenants, the maximum ratio of consolidated funded debt to consolidated EBITDA steps down from 4.25:1.00 as of September 30, 2013 to 3.25:1.00 by June 30, 2015. There are also limits on the Company's and its subsidiaries' ability to, incur liens, incur additional indebtedness, make loans and investments, engage in mergers and acquisitions, engage in asset sales, declare dividends or redeem or repurchase capital stock, alter the business conducted by the Company and its subsidiaries, transact with affiliates, prepay, redeem or purchase subordinated debt and amend or otherwise alter debt agreements.
	As of September 30, 2013 and December 31, 2012, the Company was in compliance with all of its debt covenants. As of September 30, 2013, the Company had a ratio of funded debt to consolidated EBITDA of 2.16:1.00 and had $122.5 million of borrowing available under the revolving credit facility.

Fair_Value_Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2013
Fair Value Disclosures [Abstract]	'
Fair Value Measurements	'
	Fair Value Measurements. The recorded values of cash and cash equivalents, accounts receivable, accounts payable and accrued expenses approximate their fair value based on their short-term nature. Long-term debt recorded in the Company’s Condensed Consolidated Balance Sheet at September 30, 2013 was $357.8 million. The fair value of the long-term debt was determined using the quoted price technique, based on Level 2 inputs including the yields of comparable companies with similar credit characteristics, was $361.3 million.
	The Company has obligations to the former owners of Valesta, payable in cash, if certain future financial goals are met. The fair value of this contingent consideration is determined using an expected present value technique. Expected cash flows are determined using the probability - weighted average of possible outcomes that would occur should certain financial metrics be reached. There is no market data available to use in valuing the contingent consideration, therefore, the Company developed its own assumptions related to the future financial performance of the businesses to evaluate the fair value of these liabilities. As such, the contingent consideration is classified within Level 3.
	In connection with estimating the fair value of the contingent consideration, the Company develops various scenarios (base case, downside case, and upside case) and weighs each according to the probability of occurrence. The probabilities range from 5 percent to 90 percent, with the most significant weighting given to the base case at 90 percent. These scenarios are developed based on the expected financial performance of the acquired company, with revenue growth being a primary input to the calculation, which ranged from negative seven percent to negative one percent as of September 30, 2013. A change in the probability of achievement of any of these scenarios could result in a significant increase or decrease to the estimated fair value.
	The fair value is reviewed on a quarterly basis based on most recent financial performance of the most recent fiscal quarter. An analysis is performed at the end of each fiscal quarter to compare actual results to forecasted financial performance. If performance has deviated from projected levels, the valuation is updated for the latest information available.
	The significant assumptions that may materially affect the fair value are developed in conjunction with the guidance of division management to ensure that the most accurate and latest financial projections are used and compared with the most recent financial results in the fair value measurement.
	The liabilities for the contingent consideration were established at the time of the acquisition and are evaluated at each reporting period. The current liability is included in the Condensed Consolidated Balance Sheets in the current portion of accrued earn-outs and the non-current portion is included in other long-term liabilities. Fair value adjustments are included in the Condensed Consolidated Statements of Operations and Comprehensive Income in selling, general and administrative expenses.
	The assets and liabilities measured at fair value on a recurring basis are as follows (in thousands):
		As of September 30, 2013
		Fair Value Measurements Using									Total
		Quoted Prices in Active Markets for Identical Assets			Significant Other Observable Inputs			Significant Unobservable Inputs
		(Level 1)			(Level 2)			(Level 3)
	Contingent consideration	$	—		$	—		$	(2,259	)	$	(2,259	)
		As of December 31, 2012
		Fair Value Measurements Using									Total
		Quoted Prices in Active Markets for Identical Assets			Significant Other Observable Inputs			Significant Unobservable Inputs
		(Level 1)			(Level 2)			(Level 3)
	Contingent consideration	$	—		$	—		$	(7,577	)	$	(7,577	)
	Reconciliations of liabilities measured and carried at fair value on a recurring basis with the use of significant unobservable inputs (Level 3) are as follows (in thousands):
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2013			2012			2013			2012
	Contingent consideration
	Balance at beginning of period	$	(3,171	)	$	(9,317	)	$	(7,577	)	$	(9,856	)
	Payments on contingent consideration	—			—			3,425			—
	Fair value adjustment	1,039			1,038			1,931			1,408
	Foreign currency translation adjustment	(127		)	(129		)	(38		)	40
	Balance at end of period	$	(2,259	)	$	(8,408	)	$	(2,259	)	$	(8,408	)
	Certain assets and liabilities, such as goodwill, are not measured at fair value on an ongoing basis but are subject to fair value adjustments in certain circumstances (e.g., when there is evidence of impairment). For the three and nine months ended September 30, 2013, no fair value adjustments were required for non-financial assets or liabilities

Goodwill_and_Identifiable_Asse

Goodwill and Identifiable Assets	9 Months Ended
	Sep. 30, 2013
Goodwill and Intangible Assets Disclosure [Abstract]	'
Goodwill and Identifiable Intangible Assets	'
	Goodwill and Identifiable Intangible Assets. The changes in the carrying amount of goodwill for the year ended December 31, 2012 and the nine months ended September 30, 2013 were as follows (in thousands):
		Apex				Oxford				Life Sciences				Healthcare				Physician				Total
	Balance as of December 31, 2011
	Gross goodwill	$	—			$	149,483			$	27,668			$	122,230			$	51,570			$	350,951
	Accumulated impairment loss	—				—				—				(121,717		)		—				(121,717		)
		—				149,483				27,668				513				51,570				229,234
	Apex Acquisition	264,590				—				—				—				—				264,590
	Acquisition accounting	—				—				1,814				—				(9		)		1,805
	Translation adjustment	—				—				529				—				—				529
	Balance as of December 31, 2012
	Gross goodwill	264,590				149,483				30,011				122,230				51,561				617,875
	Accumulated impairment loss	—				—				—				(121,717		)		—				(121,717		)
		264,590				149,483				30,011				513				51,561				496,158
	Divestiture - gross goodwill	—				—				—				(121,717		)		—				(121,717		)
	Divestiture - accumulated impairment loss	—				—				—				121,717				—				121,717
	Translation adjustment	—				—				395				—				—				395
	Balance as of September 30, 2013
	Gross goodwill	264,590				149,483				30,406				513				51,561				496,553
	Accumulated impairment loss	—				—				—				—				—				—
		$	264,590			$	149,483			$	30,406			$	513			$	51,561			$	496,553
	As of September 30, 2013 and December 31, 2012, the Company had the following acquired intangible assets (in thousands):
				September 30, 2013												December 31, 2012
		Estimated Useful Life		Gross Carrying Amount				Accumulated Amortization				Net Carrying Amount				Gross Carrying Amount				Accumulated Amortization				Net Carrying Amount
	Intangible assets subject to amortization:
	Customer relations	3 months – 10 years		$	103,323			$	36,865			$	66,458			$	103,285			$	23,338			$	79,947
	Contractor relations	2 - 7 years		37,884				29,858				8,026				37,871				27,754				10,117
	Non-compete agreements	2 - 7 years		2,995				1,326				1,669				2,986				1,062				1,924
				144,202				68,049				76,153				144,142				52,154				91,988
	Intangible assets not subject to amortization:
	Trademarks			171,916				—				171,916				171,852				—				171,852
	Goodwill			496,553				—				496,553				496,158				—				496,158
	Total			$	812,671			$	68,049			$	744,622			$	812,152			$	52,154			$	759,998
	Amortization expense for intangible assets with finite lives was $5.2 million and $6.7 million for the three months ended September 30, 2013 and 2012, respectively. Amortization expense for intangible assets with finite lives was $15.9 million and $11.2 million for the nine months ended September 30, 2013 and 2012, respectively. Estimated amortization for the remainder of this fiscal year, each of the next four fiscal years and thereafter follows (in thousands):
	2013	$	5,143
	2014	16,822
	2015	14,304
	2016	12,368
	2017	8,996
	Thereafter	18,520
		$	76,153
	Goodwill and other intangible assets having an indefinite useful life are not amortized for financial statement purposes. Goodwill and intangible assets with indefinite lives are reviewed for impairment on an annual basis as of October 31 and whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. There were no triggering events that required an interim impairment analysis during the current period.

Incentive_Award_Plan_and_Emplo

Incentive Award Plan and Employee Stock Purchase Plan	9 Months Ended
	Sep. 30, 2013
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]	'
Incentive Award Plan and Employee Stock Purchase Plan	'
	Incentive Award Plan and Employee Stock Purchase Plan.  On March 4, 2013, the Chief Executive Officer (the "CEO") was awarded 143,182 restricted stock units ("RSUs") with a grant date fair market value of $3.2 million, which will vest in three equal annual increments on January 4, 2014, January 4, 2015 and January 4, 2016, contingent upon the Company achieving certain performance objectives based on Adjusted EBITDA (earnings before interest, taxes, depreciation, and amortization of identifiable intangible assets, but excluding gains, losses or expenses associated with unusual items such as equity-based compensation expense, impairment charges and acquisition related costs) during 2013. On March 4, 2013, the CEO was awarded a performance-based award which had a grant date fair market value of $1.0 million. The number of shares will be determined by dividing $0.5 million by the closing price of the Company’s stock on each of February 1, 2014 and February 1, 2015, contingent upon the Company meeting certain financial performance objectives during 2013. The Company classifies this award as a liability award until the number of shares is determined. The grant-date fair market value of the RSUs described in this paragraph is expensed over the vesting term, based on an estimate of the percentage achievement of the applicable performance targets. All awards are subject to the CEO’s continued employment through applicable vesting dates. All awards may vest on an accelerated basis in part or in full upon the occurrence of certain events.
	In the first quarter of 2013, the Company granted RSUs to certain other executive officers with an aggregate grant-date fair value of $2.0 million. Of the $2.0 million, $1.0 million will vest in three equal annual increments subject to continued employment on each succeeding grant-date anniversary. The remaining $1.0 million vests on January 2, 2014, subject to continued employment and the Company attaining certain performance objectives during 2013, as approved by the Compensation Committee. Compensation expense for the performance-based component of these awards is recognized over the vesting period, based on an estimate of the percentage achievement of the targets for these awards.
	In the second quarter of 2013, the Company granted RSUs to certain executive officers. The aggregate grant-date fair value of these grants was $0.9 million. Of the $0.9 million, $0.5 million will vest in three equal annual increments subject to continued employment on each succeeding grant-date anniversary; $0.3 million will vest on May 31, 2014, subject to continued employment, attaining certain performance objectives and certification by the Compensation Committee; and the remaining $0.1 million will vest on January 2, 2014, subject to continued employment, attaining certain performance objectives and certification by the Compensation Committee. Compensation expense for the performance-based component of these awards is recognized over the vesting period, based on an estimate of the percentage achievement of the targets for these awards.
	On May 15, 2013, the Company granted 99,900 RSUs with an aggregate grant-date fair value of $2.6 million to certain Apex employees. The time-based portion of the grants, 39,958 RSUs, begins to vest on the first anniversary of the grant date and in eight quarterly installments thereafter, subject to continued employment. The performance-based portion of the grants, 59,942 RSUs, will vest, if the performance objective is attained, in 12 equal installments beginning on April 1, 2014 and on each quarterly anniversary thereafter, subject to continued employment through each vesting date.
	On March 30, 2013 the Company issued 104,328 shares of common stock under the On Assignment 2010 Employee Stock Purchase Plan (the "ESPP"). On September 30, 2013 the Company issued 98,872 shares of common stock under the ESPP.
	Compensation expense related to stock-based compensation, including the ESPP, was $4.2 million and $3.1 million for the three months ended September 30, 2013 and 2012. Compensation expense related to stock-based compensation, including the ESPP, was $10.2 million and $6.5 million for the nine months ended September 30, 2013 and 2012, respectively. Stock-based compensation is included in the Condensed Consolidated Statements of Operations and Comprehensive Income in selling, general and administrative expenses.

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2013
Commitments and Contingencies Disclosure [Abstract]	'
Commitments and Contingencies	'
	Commitments and Contingencies. The Company is partially self-insured for its workers’ compensation and medical malpractice liabilities. The Company accounts for claims incurred, but not reported based on estimates derived from historical claims experience and current trends of industry data. Changes or differences in estimates and actual payments for claims are recognized in the period that the estimates changed or the payments were made. The self-insurance claim liability was approximately $11.7 million and $10.3 million as of September 30, 2013 and December 31, 2012, respectively. The Company also has outstanding letters of credit securing obligations for workers’ compensation claims with various insurance carriers of $2.5 million as of September 30, 2013 and $2.8 million as of December 31, 2012.
	The Company is involved in various legal proceedings, claims and litigation arising in the ordinary course of business. Based on the facts currently available, the Company does not believe that the disposition of matters that are pending or asserted will have a material effect on its financial position, results of operations or cash flows.
	The Company is subject to earn-out obligations entered into in connection with certain of its acquisitions. If the acquired businesses meet predetermined targets, the Company is obligated to make additional cash payments in accordance with the terms of such earn-out obligations. As of September 30, 2013, the Company has potential future earn-out obligations of approximately $3.2 million through 2013.
	The Company has entered into various non-cancelable operating leases, primarily related to its facilities and certain office equipment used in the ordinary course of business. The Company leases two properties owned by related parties.

Earnings_per_share

Earnings per share	9 Months Ended
	Sep. 30, 2013
Earnings Per Share [Abstract]	'
Earnings per share	'
	Earnings per share. Basic earnings per share are computed based upon the weighted average number of common shares outstanding. Diluted earnings per share are computed based upon the weighted average number of common shares outstanding and dilutive common share equivalents (consisting of incentive stock options, non-qualified stock options and restricted stock awards and units and employee stock purchase plan shares) outstanding during the periods using the treasury stock method.
	The following is a reconciliation of the shares used to compute basic and diluted earnings per share (in thousands):
		Three Months Ended		Nine Months Ended
		September 30,		September 30,
		2013	2012	2013	2012
	Weighted average number of common shares outstanding used to compute basic earnings per share	53,620	52,131	53,350	44,777
	Dilutive effect of stock-based awards	1,004	1,031	1,044	1,030
	Number of shares used to compute diluted earnings per share	54,624	53,162	54,394	45,807
	The following table presents the weighted average share equivalents outstanding during each period that were excluded from the computation of diluted earnings per share because the exercise price for these options was greater than the average market price of the Company’s shares of common stock during the respective periods that became anti-dilutive when applying the treasury stock method (in thousands):
		Three Months Ended		Nine Months Ended
		September 30,		September 30,
		2013	2012	2013	2012
	Anti-dilutive common share equivalents outstanding	97	170	964	49

Income_Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2013
Income Tax Disclosure [Abstract]	'
Income Taxes	'
	Income Taxes. For interim reporting periods, the Company prepares an estimate of the full-year income and the related income tax expense for each jurisdiction in which the Company operates. Changes in the geographical mix, permanent differences or estimated level of annual pretax income can impact the Company’s actual effective rate.

Segment_Reporting

Segment Reporting	9 Months Ended
	Sep. 30, 2013
Segment Reporting [Abstract]	'
Segment Reporting	'
	11. Segment Reporting. The Company has five reportable segments: Apex, Oxford, Life Sciences, Physician, and Healthcare. The Company’s management evaluates the performance of each segment primarily based on revenues, gross profit and operating income. The information in the following table is derived directly from the segments’ internal financial reporting used for corporate management purposes.
	The following table presents revenues, gross profit and operating income by reportable segment (in thousands):
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2013			2012			2013			2012
	Revenues:
	Apex	$	246,369		$	202,664		$	692,543		$	301,167
	Oxford	100,005			88,104			296,741			254,970
	Life Sciences	44,124			40,646			126,474			122,506
	Physician	26,223			27,479			78,991			76,607
	Healthcare	15,450			15,618			44,538			41,884
		$	432,171		$	374,511		$	1,239,287		$	797,134
	Gross Profit:
	Apex	$	69,448		$	56,934		$	188,963		$	83,917
	Oxford	34,660			31,250			101,316			90,266
	Life Sciences	14,306			14,002			41,528			41,649
	Physician	7,382			8,370			22,505			23,587
	Healthcare	4,820			5,075			14,145			13,498
		$	130,616		$	115,631		$	368,457		$	252,917
	Operating Income (Loss):
	Apex	$	20,021		$	13,204		$	46,531		$	9,556
	Oxford	14,084			13,251			39,509			36,007
	Life Sciences	2,146			3,020			4,093			8,291
	Physician	1,416			3,207			5,497			6,269
	Healthcare	(779		)	(1,154		)	(2,170		)	(3,745		)
		$	36,888		$	31,528		$	93,460		$	56,378
	The Company operates internationally, with operations mainly in the United States, Europe, Canada, Australia and New Zealand. The following table presents domestic and foreign revenues (in thousands):
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2013			2012			2013			2012
	Revenues:
	Domestic	$	411,817		$	354,831		$	1,179,417		$	739,150
	Foreign	20,354			19,680			59,870			57,984
		$	432,171		$	374,511		$	1,239,287		$	797,134
	The Company does not report Life Sciences and Healthcare segments’ total assets separately as the field operations are largely combined. The following table presents total assets as allocated by reportable segment (in thousands):
		September 30, 2013			December 31, 2012
	Total Assets:
	Apex	$	664,284		$	642,594
	Oxford	240,911			231,211
	Life Sciences and Healthcare	132,008			139,601
	Physician	81,279			84,615
		$	1,118,482		$	1,098,021

Acquisitions_Business_Combinat

Acquisitions Business Combinations (Policies)	9 Months Ended
	Sep. 30, 2013
Business Combinations [Abstract]	'
Fair Value Assigned to Identifiable Intangible Assets	'
	The fair value assigned to identifiable intangible assets was determined primarily by using a discounted cash flow method.

Fair_Value_Measurements_Polici

Fair Value Measurements (Policies)	9 Months Ended
	Sep. 30, 2013
Fair Value Disclosures [Abstract]	'
Fair Value of Financial Instruments, Policy [Policy Text Block]	'
	The recorded values of cash and cash equivalents, accounts receivable, accounts payable and accrued expenses approximate their fair value based on their short-term nature. Long-term debt recorded in the Company’s Condensed Consolidated Balance Sheet at September 30, 2013 was $357.8 million. The fair value of the long-term debt was determined using the quoted price technique, based on Level 2 inputs including the yields of comparable companies with similar credit characteristics, was $361.3 million.
Fair Value of Contingent Consideration	'
	The Company has obligations to the former owners of Valesta, payable in cash, if certain future financial goals are met. The fair value of this contingent consideration is determined using an expected present value technique. Expected cash flows are determined using the probability - weighted average of possible outcomes that would occur should certain financial metrics be reached. There is no market data available to use in valuing the contingent consideration, therefore, the Company developed its own assumptions related to the future financial performance of the businesses to evaluate the fair value of these liabilities. As such, the contingent consideration is classified within Level 3.
	In connection with estimating the fair value of the contingent consideration, the Company develops various scenarios (base case, downside case, and upside case) and weighs each according to the probability of occurrence. The probabilities range from 5 percent to 90 percent, with the most significant weighting given to the base case at 90 percent. These scenarios are developed based on the expected financial performance of the acquired company, with revenue growth being a primary input to the calculation, which ranged from negative seven percent to negative one percent as of September 30, 2013. A change in the probability of achievement of any of these scenarios could result in a significant increase or decrease to the estimated fair value.
	The fair value is reviewed on a quarterly basis based on most recent financial performance of the most recent fiscal quarter. An analysis is performed at the end of each fiscal quarter to compare actual results to forecasted financial performance. If performance has deviated from projected levels, the valuation is updated for the latest information available.
	The significant assumptions that may materially affect the fair value are developed in conjunction with the guidance of division management to ensure that the most accurate and latest financial projections are used and compared with the most recent financial results in the fair value measurement.
	The liabilities for the contingent consideration were established at the time of the acquisition and are evaluated at each reporting period. The current liability is included in the Condensed Consolidated Balance Sheets in the current portion of accrued earn-outs and the non-current portion is included in other long-term liabilities. Fair value adjustments are included in the Condensed Consolidated Statements of Operations and Comprehensive Income in selling, general and administrative expenses.

Acquisitions_Tables

Acquisitions (Tables)	9 Months Ended
	Sep. 30, 2013
Business Combinations [Abstract]	'
Schedule of Purchase Price Allocation	'
	The following table summarizes (in thousands) the final purchase price allocation for the acquisition of Apex:
	Current assets		$	172,042
	Property and equipment		902
	Goodwill		264,590
	Identifiable intangible assets		251,555
	Other		494
	Total assets acquired		$	689,583
	Current liabilities		$	77,905
	Other		850
	Total liabilities assumed		78,755
	Total purchase price		$	610,828
Schedule of Intangible Assets Acquired as Part of Business Combinations	'
	The following table summarizes (in thousands) the allocation of the purchase price among the identifiable intangible assets for the acquisition of Apex:
		Useful life		Identifiable Intangible Asset Value
	Contractor relationships	5 years		$	10,589
	Customer relationships	10 years		92,147
	Non-compete agreements	7 years		2,076
	Trademarks	indefinite		146,743
	Total identifiable intangible assets acquired			$	251,555
Schedule of Pro Forma Consolidated Results of Operations	'
	Revenues	$	1,079,411
	Income from continuing operations	$	37,215
	Net income	$	39,883
	Basic earnings per share:
	Income from continuing operations	$	0.72
	Net income	$	0.77
	Diluted earnings per share:
	Income from continuing operations	$	0.7
	Net income	$	0.75
	Weighted average number of shares outstanding	51,929
	Weighted average number of shares and dilutive shares outstanding	52,959

Discontinued_Operations_Discon1

Discontinued Operations Discontinued Operations (Tables)	9 Months Ended
	Sep. 30, 2013
Discontinued Operations [Abstract]	'
Schedule of Disposal Groups, Including Discontinued Operations, Income Statement, Balance Sheet and Additional Disclosures [Table Text Block]	'
	The following is a summary of the Nurse Travel division's operating results (in thousands):
		Three Months Ended					Nine Months Ended
		September 30,					September 30,
		2013			2012		2013			2012
	Revenues	$	—		$	13,772	$	6,408		$	40,912
	Income (loss) before income taxes	$	(119	)	$	1,347	$	(1,398	)	$	4,288
	Provision (benefit) for income taxes	$	(60	)	$	500	$	(447	)	$	1,620
	Net income (loss)	$	(59	)	$	847	$	(951	)	$	2,668

LongTerm_Debt_Tables

Long-Term Debt (Tables)	9 Months Ended
	Sep. 30, 2013
Debt Disclosure [Abstract]	'
Schedule of Long-term Debt	'
	Long-term debt consisted of the following (in thousands):
		September 30,			December 31, 2012
		2013
	Senior Secured Debt
	$125 million revolving credit facility, due May 2018	$	—		$	—
	$100 million term A loan facility, due May 2018	95,000			—
	$275 million term B loan facility, due May 2020	262,813			—
	$75 million revolving credit facility, repaid May 2013	—			—
	$100 million term A loan facility, repaid May 2013	—			92,500
	$365 million term B loan facility, repaid May 2013	—			334,088
		$	357,813		$	426,588
Contractual Obligation, Fiscal Year Maturity Schedule [Table Text Block]	'
	During the remainder of this fiscal year, each of the next four years and thereafter, the Company will be required to make payments as follows (in thousands):
	2013		$	2,500
	2014		10,000
	2015		10,000
	2016		10,000
	2017		10,875
	Thereafter		314,438
	Total		$	357,813

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2013
Fair Value Disclosures [Abstract]	'
Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis	'
	The assets and liabilities measured at fair value on a recurring basis are as follows (in thousands):
		As of September 30, 2013
		Fair Value Measurements Using									Total
		Quoted Prices in Active Markets for Identical Assets			Significant Other Observable Inputs			Significant Unobservable Inputs
		(Level 1)			(Level 2)			(Level 3)
	Contingent consideration	$	—		$	—		$	(2,259	)	$	(2,259	)
		As of December 31, 2012
		Fair Value Measurements Using									Total
		Quoted Prices in Active Markets for Identical Assets			Significant Other Observable Inputs			Significant Unobservable Inputs
		(Level 1)			(Level 2)			(Level 3)
	Contingent consideration	$	—		$	—		$	(7,577	)	$	(7,577	)
Schedule of Reconciliations of Liabilities Measured and Carried at Fair Value on Recurring Basis, with Significant Unobservable Inputs	'
	Reconciliations of liabilities measured and carried at fair value on a recurring basis with the use of significant unobservable inputs (Level 3) are as follows (in thousands):
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2013			2012			2013			2012
	Contingent consideration
	Balance at beginning of period	$	(3,171	)	$	(9,317	)	$	(7,577	)	$	(9,856	)
	Payments on contingent consideration	—			—			3,425			—
	Fair value adjustment	1,039			1,038			1,931			1,408
	Foreign currency translation adjustment	(127		)	(129		)	(38		)	40
	Balance at end of period	$	(2,259	)	$	(8,408	)	$	(2,259	)	$	(8,408	)

Goodwill_and_Identifiable_Asse1

Goodwill and Identifiable Assets (Tables)	9 Months Ended
	Sep. 30, 2013
Goodwill and Intangible Assets Disclosure [Abstract]	'
Schedule of Goodwill	'
	The changes in the carrying amount of goodwill for the year ended December 31, 2012 and the nine months ended September 30, 2013 were as follows (in thousands):
		Apex				Oxford				Life Sciences				Healthcare				Physician				Total
	Balance as of December 31, 2011
	Gross goodwill	$	—			$	149,483			$	27,668			$	122,230			$	51,570			$	350,951
	Accumulated impairment loss	—				—				—				(121,717		)		—				(121,717		)
		—				149,483				27,668				513				51,570				229,234
	Apex Acquisition	264,590				—				—				—				—				264,590
	Acquisition accounting	—				—				1,814				—				(9		)		1,805
	Translation adjustment	—				—				529				—				—				529
	Balance as of December 31, 2012
	Gross goodwill	264,590				149,483				30,011				122,230				51,561				617,875
	Accumulated impairment loss	—				—				—				(121,717		)		—				(121,717		)
		264,590				149,483				30,011				513				51,561				496,158
	Divestiture - gross goodwill	—				—				—				(121,717		)		—				(121,717		)
	Divestiture - accumulated impairment loss	—				—				—				121,717				—				121,717
	Translation adjustment	—				—				395				—				—				395
	Balance as of September 30, 2013
	Gross goodwill	264,590				149,483				30,406				513				51,561				496,553
	Accumulated impairment loss	—				—				—				—				—				—
		$	264,590			$	149,483			$	30,406			$	513			$	51,561			$	496,553
Schedule of Acquired Intangible Assets	'
	As of September 30, 2013 and December 31, 2012, the Company had the following acquired intangible assets (in thousands):
				September 30, 2013												December 31, 2012
		Estimated Useful Life		Gross Carrying Amount				Accumulated Amortization				Net Carrying Amount				Gross Carrying Amount				Accumulated Amortization				Net Carrying Amount
	Intangible assets subject to amortization:
	Customer relations	3 months – 10 years		$	103,323			$	36,865			$	66,458			$	103,285			$	23,338			$	79,947
	Contractor relations	2 - 7 years		37,884				29,858				8,026				37,871				27,754				10,117
	Non-compete agreements	2 - 7 years		2,995				1,326				1,669				2,986				1,062				1,924
				144,202				68,049				76,153				144,142				52,154				91,988
	Intangible assets not subject to amortization:
	Trademarks			171,916				—				171,916				171,852				—				171,852
	Goodwill			496,553				—				496,553				496,158				—				496,158
	Total			$	812,671			$	68,049			$	744,622			$	812,152			$	52,154			$	759,998
Schedule of Estimated Future Amortization Expense	'
	Estimated amortization for the remainder of this fiscal year, each of the next four fiscal years and thereafter follows (in thousands):
	2013	$	5,143
	2014	16,822
	2015	14,304
	2016	12,368
	2017	8,996
	Thereafter	18,520
		$	76,153

Earnings_per_share_Tables

Earnings per share (Tables)	9 Months Ended
	Sep. 30, 2013
Earnings Per Share [Abstract]	'
Reconciliation of Shares Used to Compute Basic and Diluted Earnings per Share	'
	The following is a reconciliation of the shares used to compute basic and diluted earnings per share (in thousands):
		Three Months Ended		Nine Months Ended
		September 30,		September 30,
		2013	2012	2013	2012
	Weighted average number of common shares outstanding used to compute basic earnings per share	53,620	52,131	53,350	44,777
	Dilutive effect of stock-based awards	1,004	1,031	1,044	1,030
	Number of shares used to compute diluted earnings per share	54,624	53,162	54,394	45,807
Schedule of Weighted Average Share Equivalents Outstanding Excluded from Computation of Diluted Earnings per Share	'
	The following table presents the weighted average share equivalents outstanding during each period that were excluded from the computation of diluted earnings per share because the exercise price for these options was greater than the average market price of the Company’s shares of common stock during the respective periods that became anti-dilutive when applying the treasury stock method (in thousands):
		Three Months Ended		Nine Months Ended
		September 30,		September 30,
		2013	2012	2013	2012
	Anti-dilutive common share equivalents outstanding	97	170	964	49

Segment_Reporting_Tables

Segment Reporting (Tables)	9 Months Ended
	Sep. 30, 2013
Segment Reporting [Abstract]	'
Schedule of Segment Reporting Information, by Segment	'
	The following table presents revenues, gross profit and operating income by reportable segment (in thousands):
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2013			2012			2013			2012
	Revenues:
	Apex	$	246,369		$	202,664		$	692,543		$	301,167
	Oxford	100,005			88,104			296,741			254,970
	Life Sciences	44,124			40,646			126,474			122,506
	Physician	26,223			27,479			78,991			76,607
	Healthcare	15,450			15,618			44,538			41,884
		$	432,171		$	374,511		$	1,239,287		$	797,134
	Gross Profit:
	Apex	$	69,448		$	56,934		$	188,963		$	83,917
	Oxford	34,660			31,250			101,316			90,266
	Life Sciences	14,306			14,002			41,528			41,649
	Physician	7,382			8,370			22,505			23,587
	Healthcare	4,820			5,075			14,145			13,498
		$	130,616		$	115,631		$	368,457		$	252,917
	Operating Income (Loss):
	Apex	$	20,021		$	13,204		$	46,531		$	9,556
	Oxford	14,084			13,251			39,509			36,007
	Life Sciences	2,146			3,020			4,093			8,291
	Physician	1,416			3,207			5,497			6,269
	Healthcare	(779		)	(1,154		)	(2,170		)	(3,745		)
		$	36,888		$	31,528		$	93,460		$	56,378
Schedule of Revenue by Geographical Areas	'
	The Company operates internationally, with operations mainly in the United States, Europe, Canada, Australia and New Zealand. The following table presents domestic and foreign revenues (in thousands):
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2013			2012			2013			2012
	Revenues:
	Domestic	$	411,817		$	354,831		$	1,179,417		$	739,150
	Foreign	20,354			19,680			59,870			57,984
		$	432,171		$	374,511		$	1,239,287		$	797,134
Reconciliation of Assets from Segment to Consolidated	'
	The Company does not report Life Sciences and Healthcare segments’ total assets separately as the field operations are largely combined. The following table presents total assets as allocated by reportable segment (in thousands):
		September 30, 2013			December 31, 2012
	Total Assets:
	Apex	$	664,284		$	642,594
	Oxford	240,911			231,211
	Life Sciences and Healthcare	132,008			139,601
	Physician	81,279			84,615
		$	1,118,482		$	1,098,021

Acquisitions_Acquisitions_Cost

Acquisitions (Acquisitions Costs, by Acquisition) (Details) (USD $)	3 Months Ended		9 Months Ended		0 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Jun. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	15-May-12	Dec. 31, 2012
					Apex Systems	Apex Systems
Business Acquisition [Line Items]	'	'	'	'	'	'
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Assets	$2.20	$3.40	'	$5	'	'
Business Combination Provisional Information Initial Accounting Incomplete Adjustment, Financial Assets, Net of Taxes	'	1.9	'	2.9	'	'
Effective Date of Acquisition	'	'	'	'	15-May-12	'
Name of Acquired Entity	'	'	'	'	'Apex Systems, Inc.	'
Business Acquisition, Description of Acquired Entity	'	'	'	'	'a privately-owned provider of information technology staffing services headquartered in Richmond, Virginia	'
Reason for Business Combination	'	'	'	'	' The primary reason for the acquisition was to expand the Company's information technology staffing services.	'
Cost of acquired entity, purchase price	'	'	'	'	610.8	'
Cost of acquired entity, cash paid	'	'	'	'	385.3	'
Shares of Company's common stock issued (in shares)	'	'	'	'	14.3	'
Acquisition costs expensed	'	'	'	'	'	$9.80
Purchase Price Allocation, Methodology	'	'	'Assets and liabilities of the acquired company were recorded at their estimated fair values at the date of acquisition. The excess purchase price over the fair value of net tangible assets and identifiable intangible assets acquired has been allocated to goodwill.	'	'	'
Purchase Price Allocation, Status	'the Company finalized the allocation of the purchase price	'	'	'	'	'

Acquisitions_Schedule_of_Purch

Acquisitions (Schedule of Purchase Price Allocation) (Details) (USD $)	3 Months Ended		9 Months Ended
	Jun. 30, 2013	Sep. 30, 2012	Sep. 30, 2012	15-May-12
				Apex Systems
Business Acquisition [Line Items]	'	'	'	'
Purchase Price Allocation, Status	'the Company finalized the allocation of the purchase price	'	'	'
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Assets	$2,200,000	$3,400,000	$5,000,000	'
Business Combination Provisional Information Initial Accounting Incomplete Adjustment, Financial Assets, Net of Taxes	'	1,900,000	2,900,000	'
Current assets	'	'	'	172,042,000
Property and equipment	'	'	'	902,000
Goodwill	'	'	'	264,590,000
Identifiable intangible assets	'	'	'	251,555,000
Other	'	'	'	494,000
Total assets acquired	'	'	'	689,583,000
Current liabilities	'	'	'	77,905,000
Other	'	'	'	850,000
Total liabilities assumed	'	'	'	78,755,000
Total purchase price	'	'	'	$610,828,000

Acquisitions_Schedule_of_Intan

Acquisitions (Schedule of Intangible Assets Acquired as Part of Business Combination) (Details) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2013	15-May-12	15-May-12	15-May-12	15-May-12	15-May-12
	Contractor relations	Customer relations	Non-compete agreements	Apex Systems	Apex Systems	Apex Systems	Apex Systems	Apex Systems
					Trademarks	Contractor relations	Customer relations	Non-compete agreements
Acquired Intangible Assets [Line Items]	'	'	'	'	'	'	'	'
Finite lived, Intangible asset value	'	'	'	'	'	$10,589	$92,147	$2,076
Useful life	'5 years	'10 years	'7 years	'	'	'	'	'
Indefinite lived, Intangible asset value	'	'	'	'	146,743	'	'	'
Total intangible assets acquired	'	'	'	$251,555	'	'	'	'

Acquisitions_Business_Acquisit

Acquisitions (Business Acquisition, Pro Forma Information) (Details) (USD $)	9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2012
Business Acquisition, Pro Forma Information [Abstract]	'
Business Acquisition, Pro Forma Information, Description	'The pro forma financial information gives effect to certain adjustments, including: the amortization of intangible assets, interest expense on acquisition-related debt, and increased number of common shares as a result of the acquisition. Acquisition-related costs are assumed to have occurred at the beginning of the year prior to acquisition.
Revenues	$1,079,411
Operating income	37,215
Net income	$39,883
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations before Changes in Accounting and Extraordinary Items, Net of Tax, Per Share, Basic	$0.72
Basic earnings per share (in dollars per share)	$0.77
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations before Changes in Accounting and Extraordinary Items, Net of Tax, Per Share, Diluted	$0.70
Diluted earnings per share (in dollars per share)	$0.75
Weighted average number of shares outstanding	51,929
Weighted average number of shares and dilutive shares outstanding	52,959

Discontinued_Operations_Discon2

Discontinued Operations Discontinued Operations (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Discontinued Operations and Disposal Groups [Abstract]	'	'	'	'
Proceeds from Divestiture of Businesses	'	'	$33,700,000	'
Gain on sale of discontinued operations, net of income taxes	0	0	14,412,000	0
Disposal Group, Including Discontinued Operation, Revenue	0	13,772,000	6,408,000	40,912,000
Disposal Group, Including Discontinued Operation, Operating Income (Loss)	-119,000	1,347,000	-1,398,000	4,288,000
Discontinued Operation, Tax Effect of Discontinued Operation	-60,000	500,000	-447,000	1,620,000
Income (loss) from discontinued operations, net of income taxes	($59,000)	$847,000	($951,000)	$2,668,000

LongTerm_Debt_Details

Long-Term Debt (Details) (USD $)

0 Months Ended

0 Months Ended

0 Months Ended

Sep. 30, 2013

Dec. 31, 2012

16-May-13

Sep. 30, 2013

16-May-13

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

16-May-13

Sep. 30, 2013

16-May-13

Sep. 30, 2013

Sep. 30, 2013

Dec. 31, 2012

16-May-13

16-May-13

Sep. 30, 2013

16-May-13

16-May-13

16-May-13

16-May-13

16-May-13

Term A Loans, Term B Loans and Revolving Loans [Member]

Notes Payable to Banks [Member]

Notes Payable to Banks [Member]

Notes Payable to Banks [Member]

Notes Payable to Banks [Member]

Notes Payable to Banks [Member]

Notes Payable to Banks [Member]

Notes Payable to Banks [Member]

Notes Payable to Banks [Member]

Notes Payable to Banks [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Revolving Credit Facility [Member]

Eurodollar [Member]

Maximum [Member]

Maximum [Member]

Maximum [Member]

Minimum [Member]

Minimum [Member]

Minimum [Member]

Term-B Loan Facility due May 2020 [Member]

Term-B Loan Facility due May 2020 [Member]

Term-A Loan Facility due May 2017 [Member]

Term-A Loan Facility due May 2017 [Member]

Term-B Loan Facility due May 2019 [Member]

Term-B Loan Facility due May 2019 [Member]

Senior Secured Credit Agreement [Member]

Term-A Loan Facility due May 2018 [Member]

Term-A Loan Facility due May 2018 [Member]

Revolving Credit Facility due May 2017 [Member]

Revolving Credit Facility due May 2017 [Member]

Revolving Credit Facility due May 2018 [Member]

Notes Payable to Banks [Member]

Revolving Credit Facility [Member]

Eurodollar [Member]

Revolving Credit Facility [Member]

Eurodollar [Member]

Eurodollar [Member]

Term-B Loan Facility due May 2020 [Member]

Revolving Credit Facility due May 2018 [Member]

Notes Payable to Banks [Member]

Revolving Credit Facility due May 2018 [Member]

Notes Payable to Banks [Member]

Notes Payable to Banks [Member]

Revolving Loans and Term A Loans [Member]

Revolving Loans and Term A Loans [Member]

Term-B Loan Facility due May 2020 [Member]

Debt Disclosure [Abstract]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Long-term Debt, Maturities, Repayments of Principal, Remainder of Fiscal Year

$2,500,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Long-term Debt, Maturities, Repayments of Principal in Year Two

10,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Long-term Debt, Maturities, Repayments of Principal in Year Three

10,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Long-term Debt, Maturities, Repayments of Principal in Year Four

10,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Long-term Debt, Maturities, Repayments of Principal in Year Five

10,875,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Long-term Debt, Maturities, Repayments of Principal in Rolling after Year Five

314,438,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Long-term Debt

357,813,000

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Debt Instrument [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Line of Credit Facility, Increase in Additional Principal Amount

'

'

'

'

'

'

'

'

'

100,000,000

'

'

'

'

'

'

'

'

'

'

'

'

'

Leverage Ratio in Latest Year of Debt Term

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

3.25

'

'

'

'

'

Debt Instrument, Basis Spread on Variable Rate

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

2.50%

'

'

2.50%

'

1.75%

1.00%

Line of Credit Facility, Unused Capacity, Commitment Fee Percentage

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

0.40%

'

0.25%

'

'

Debt Instrument, Face Amount

'

'

'

'

275,000,000

'

'

'

'

'

'

100,000,000

'

'

'

'

'

'

'

'

'

'

'

Senior Secured Debt

357,813,000

426,588,000

'

262,813,000

'

0

92,500,000

0

334,088,000

'

95,000,000

'

'

0

0

'

'

'

'

'

'

'

'

Line of Credit Facility, Maximum Borrowing Capacity

'

'

500,000,000

'

'

'

'

'

'

'

'

'

'

'

'

125,000,000

'

'

'

'

'

'

'

Line of Credit Facility, Remaining Borrowing Capacity

'

'

'

'

'

'

'

'

'

'

'

'

$122,500,000

'

'

'

'

'

'

'

'

'

'

Debt Instrument, Interest Rate at Period End

'

'

'

3.50%

'

'

'

'

'

'

2.20%

'

'

'

'

'

'

'

'

'

'

'

'

Leverage Ratio

2.16

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

4.25

'

'

'

'

'

Debt, Weighted Average Interest Rate

3.20%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Pledged equity interest in foreign subsidiaries

65.00%

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Fair_Value_Measurements_Fair_V

Fair Value Measurements (Fair Value Inputs, Liabilities, Quantitative Information) (Details) (USD $)	3 Months Ended
	Sep. 30, 2013
Fair Value Inputs, Liabilities, Quantitative Information	'
Long-term Debt	357,813,000
Level 2 Inputs	'
Fair Value Inputs, Liabilities, Quantitative Information	'
Long-term debt, fair value	361,300,000
Significant Unobservable Inputs (Level 3) | Contingent Consideration Liability | Minimum	'
Fair Value Inputs, Liabilities, Quantitative Information	'
Probability of occurrence of scenarios (as a percentage)	5.00%
Revenue growth rates (as a percentage)	-7.00%
Significant Unobservable Inputs (Level 3) | Contingent Consideration Liability | Maximum	'
Fair Value Inputs, Liabilities, Quantitative Information	'
Probability of occurrence of scenarios (as a percentage)	90.00%
Weighting given to base case scenario (as a percentage)	90.00%
Revenue growth rates (as a percentage)	-1.00%

Fair_Value_Measurements_Recurr

Fair Value Measurements (Recurring Basis) (Details) (Recurring Basis, USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Quoted Prices in Active Markets for Identical Assets (Level 1)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Contingent consideration to be paid in cash for the acquisitions	$0	$0
Significant Other Observable Inputs (Level 2)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Contingent consideration to be paid in cash for the acquisitions	0	0
Significant Unobservable Inputs (Level 3)	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Contingent consideration to be paid in cash for the acquisitions	-2,259	-7,577
Total Fair Value	'	'
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis	'	'
Contingent consideration to be paid in cash for the acquisitions	($2,259)	($7,577)

Fair_Value_Measurements_Liabil

Fair Value Measurements (Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation) (Details) (Contingent Consideration Liability, USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Contingent Consideration Liability	'	'	'	'
Contingent consideration for acquisitions	'	'	'	'
Balance at beginning of period	($3,171)	($9,317)	($7,577)	($9,856)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Payments	0	0	3,425	0
Fair value adjustment	1,039	1,038	1,931	1,408
Foreign currency translation adjustment	-127	-129	-38	40
Balance at end of period	($2,259)	($8,408)	($2,259)	($8,408)

Goodwill_and_Identifiable_Asse2

Goodwill and Identifiable Assets (Goodwill) (Details) (USD $)	9 Months Ended		12 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011
Goodwill [Roll Forward]	'	'	'	'
Gross goodwill	$496,553	'	$617,875	$350,951
Accumulated impairment loss	0	'	-121,717	-121,717
Goodwill	496,553	'	496,158	229,234
Acquisition	'	'	264,590	'
Goodwill, Purchase Accounting Adjustments	0	-982	1,805	'
Goodwill, Written off Related to Sale of Business Unit	-121,717	'	'	'
Write-off of accum impairment loss related to sale of business unit	121,717	'	'	'
Translation adjustment	395	'	529	'
Apex	'	'	'	'
Goodwill [Roll Forward]	'	'	'	'
Gross goodwill	264,590	'	264,590	0
Accumulated impairment loss	0	'	0	0
Goodwill	264,590	'	264,590	0
Acquisition	'	'	264,590	'
Translation adjustment	0	'	0	'
Oxford	'	'	'	'
Goodwill [Roll Forward]	'	'	'	'
Gross goodwill	149,483	'	149,483	149,483
Accumulated impairment loss	0	'	0	0
Goodwill	149,483	'	149,483	149,483
Translation adjustment	0	'	0	'
Life Sciences	'	'	'	'
Goodwill [Roll Forward]	'	'	'	'
Gross goodwill	30,406	'	30,011	27,668
Accumulated impairment loss	0	'	0	0
Goodwill	30,406	'	30,011	27,668
Acquisition	'	'	0	'
Goodwill, Purchase Accounting Adjustments	'	'	1,814	'
Translation adjustment	395	'	529	'
Healthcare	'	'	'	'
Goodwill [Roll Forward]	'	'	'	'
Gross goodwill	513	'	122,230	122,230
Accumulated impairment loss	0	'	-121,717	-121,717
Goodwill	513	'	513	513
Goodwill, Written off Related to Sale of Business Unit	-121,717	'	'	'
Write-off of accum impairment loss related to sale of business unit	121,717	'	'	'
Translation adjustment	0	'	0	'
Physician	'	'	'	'
Goodwill [Roll Forward]	'	'	'	'
Gross goodwill	51,561	'	51,561	51,570
Accumulated impairment loss	0	'	0	0
Goodwill	51,561	'	51,561	51,570
Translation adjustment	0	'	0	'
Physician | Health Care Partners [Member]	'	'	'	'
Goodwill [Roll Forward]	'	'	'	'
Goodwill, Purchase Accounting Adjustments	'	'	($9)	'

Goodwill_and_Identifiable_Asse3

Goodwill and Identifiable Assets (Acquired Intangible Assets) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Dec. 31, 2011
Intangible Assets [Line Items]	'	'	'	'	'	'
Amortization of intangible assets	$5,199	$6,679	$15,853	$11,197	'	'
Intangible assets subject to amortization:	'	'	'	'	'	'
Gross Carrying Amount	144,202	'	144,202	'	144,142	'
Accumulated Amortization	68,049	'	68,049	'	52,154	'
Net Carrying Amount	76,153	'	76,153	'	91,988	'
Intangible assets not subject to amortization:	'	'	'	'	'	'
Trademarks, Carrying Amount	171,916	'	171,916	'	171,852	'
Goodwill, Carrying Amount	496,553	'	496,553	'	496,158	229,234
Total	'	'	'	'	'	'
Gross Carrying Amount	812,671	'	812,671	'	812,152	'
Net Carrying Amount	744,622	'	744,622	'	759,998	'
Customer relations	'	'	'	'	'	'
Intangible assets subject to amortization:	'	'	'	'	'	'
Gross Carrying Amount	103,323	'	103,323	'	103,285	'
Accumulated Amortization	36,865	'	36,865	'	23,338	'
Net Carrying Amount	66,458	'	66,458	'	79,947	'
Customer relations | Minimum	'	'	'	'	'	'
Intangible Assets [Line Items]	'	'	'	'	'	'
Estimated Useful Life	'	'	'3 months	'	'	'
Customer relations | Maximum	'	'	'	'	'	'
Intangible Assets [Line Items]	'	'	'	'	'	'
Estimated Useful Life	'	'	'10 years	'	'	'
Contractor relations	'	'	'	'	'	'
Intangible assets subject to amortization:	'	'	'	'	'	'
Gross Carrying Amount	37,884	'	37,884	'	37,871	'
Accumulated Amortization	29,858	'	29,858	'	27,754	'
Net Carrying Amount	8,026	'	8,026	'	10,117	'
Contractor relations | Minimum	'	'	'	'	'	'
Intangible Assets [Line Items]	'	'	'	'	'	'
Estimated Useful Life	'	'	'2 years	'	'	'
Contractor relations | Maximum	'	'	'	'	'	'
Intangible Assets [Line Items]	'	'	'	'	'	'
Estimated Useful Life	'	'	'7 years	'	'	'
Non-compete agreements	'	'	'	'	'	'
Intangible assets subject to amortization:	'	'	'	'	'	'
Gross Carrying Amount	2,995	'	2,995	'	2,986	'
Accumulated Amortization	1,326	'	1,326	'	1,062	'
Net Carrying Amount	$1,669	'	$1,669	'	$1,924	'
Non-compete agreements | Minimum	'	'	'	'	'	'
Intangible Assets [Line Items]	'	'	'	'	'	'
Estimated Useful Life	'	'	'2 years	'	'	'
Non-compete agreements | Maximum	'	'	'	'	'	'
Intangible Assets [Line Items]	'	'	'	'	'	'
Estimated Useful Life	'	'	'7 years	'	'	'

Goodwill_and_Identifiable_Asse4

Goodwill and Identifiable Assets (Future Amortization Expense) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Goodwill and Intangible Assets Disclosure [Abstract]	'	'	'	'	'
Amortization of intangible assets	$5,199	$6,679	$15,853	$11,197	'
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]	'	'	'	'	'
2012	5,143	'	5,143	'	'
2013	16,822	'	16,822	'	'
2014	14,304	'	14,304	'	'
2015	12,368	'	12,368	'	'
2016	8,996	'	8,996	'	'
Thereafter	18,520	'	18,520	'	'
Net Carrying Amount	$76,153	'	$76,153	'	$91,988

Incentive_Award_Plan_and_Emplo1

Incentive Award Plan and Employee Stock Purchase Plan (Details) (USD $)

0 Months Ended

3 Months Ended

9 Months Ended

0 Months Ended

In Millions, except Share data, unless otherwise specified

15-May-13

Mar. 04, 2013

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Mar. 30, 2013

15-May-13

15-May-13

Mar. 04, 2013

Mar. 04, 2013

Jun. 30, 2013

Mar. 04, 2013

Jun. 30, 2013

Mar. 04, 2013

Jun. 30, 2013

Mar. 04, 2013

Jun. 30, 2013

2010 Employee Stock Purchase Plan (ESPP)

2010 Employee Stock Purchase Plan (ESPP)

Performance Based Award

Restricted Stock Units (RSUs)

Chief Executive Officer

Chief Executive Officer

Other Executive Officers

Other Executive Officers

Other Executive Officers

Other Executive Officers

Other Executive Officers

Other Executive Officers

Other Executive Officers

installment

installment

Performance Based Award

Performance Shares 2012 [Member]

Performance Based Award

Restricted Stock Units (RSUs)

Restricted Stock Units (RSUs)

Performance Shares 2013 [Member]

installment

installment

installment

Deferred Compensation Arrangement with Individual, Share-based Payments

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Share-based awards, grant date fair market value

$2.60

$3.20

'

'

'

'

'

'

'

'

$1

$0.50

$0.90

$2

$0.30

$1

$0.50

$1

$0.10

Share-based awards, grants in period

99,900

143,182

'

'

'

'

'

'

59,942

39,958

'

'

'

'

'

'

'

'

'

Share-based awards, number of equal vesting components

'

'

'

'

'

'

'

'

12

8

'

3

'

'

'

'

3

3

'

Employee stock purchase plan shares issued during period

'

'

'

'

'

'

98,872

104,328

'

'

'

'

'

'

'

'

'

'

'

Allocated Share-based Compensation Expense

'

'

$4.20

$3.10

$10.20

$6.50

'

'

'

'

'

'

'

'

'

'

'

'

'

Incentive_Award_Plan_and_Emplo2

Incentive Award Plan and Employee Stock Purchase Plan (Compensation Expense) (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Employee Service Share-based Compensation, Allocation of Recognized Period Costs	'	'	'	'
Allocated Share-based Compensation Expense	$4.20	$3.10	$10.20	$6.50

Commitments_and_Contingencies_

Commitments and Contingencies (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Millions, unless otherwise specified	property
Commitments and Contingencies Disclosure [Abstract]	'	'
Number of Leased Properties Owned by Related Parties	2	'
Self insurance claim liability	$11.70	$10.30
Letters of credit outstanding, amount	2.5	2.8
Approximate potential future earn-out obligations	$3.20	'

Earnings_per_share_Details

Earnings per share (Details)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Weighted Average Number of Shares Outstanding Reconciliation	'	'	'	'
Weighted average number of common shares outstanding used to compute basic earnings per share	53,620	52,131	53,350	44,777
Dilutive effect of stock-based awards	1,004	1,031	1,044	1,030
Number of shares used to compute diluted earnings per share	54,624	53,162	54,394	45,807

Earnings_per_share_Antidilutiv

Earnings per share Anti-dilutive (Details)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Abstract]	'	'	'	'
Anti-dilutive common share equivalents outstanding	97	170	964	49

Segment_Reporting_Segment_Repo

Segment Reporting (Segment Reporting Information) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
			segment
Segment Reporting [Abstract]	'	'	'	'
Reportable segments (in number of segments)	'	'	5	'
Revenues:	'	'	'	'
Total Revenues	$432,171	$374,511	$1,239,287	$797,134
Gross Profit:	'	'	'	'
Total Gross Profit	130,616	115,631	368,457	252,917
Operating Income (Loss):	'	'	'	'
Total Operating Income	36,888	31,528	93,460	56,378
Apex	'	'	'	'
Revenues:	'	'	'	'
Total Revenues	246,369	202,664	692,543	301,167
Gross Profit:	'	'	'	'
Total Gross Profit	69,448	56,934	188,963	83,917
Operating Income (Loss):	'	'	'	'
Total Operating Income	20,021	13,204	46,531	9,556
Oxford	'	'	'	'
Revenues:	'	'	'	'
Total Revenues	100,005	88,104	296,741	254,970
Gross Profit:	'	'	'	'
Total Gross Profit	34,660	31,250	101,316	90,266
Operating Income (Loss):	'	'	'	'
Total Operating Income	14,084	13,251	39,509	36,007
Life Sciences	'	'	'	'
Revenues:	'	'	'	'
Total Revenues	44,124	40,646	126,474	122,506
Gross Profit:	'	'	'	'
Total Gross Profit	14,306	14,002	41,528	41,649
Operating Income (Loss):	'	'	'	'
Total Operating Income	2,146	3,020	4,093	8,291
Physician	'	'	'	'
Revenues:	'	'	'	'
Total Revenues	26,223	27,479	78,991	76,607
Gross Profit:	'	'	'	'
Total Gross Profit	7,382	8,370	22,505	23,587
Operating Income (Loss):	'	'	'	'
Total Operating Income	1,416	3,207	5,497	6,269
Healthcare	'	'	'	'
Revenues:	'	'	'	'
Total Revenues	15,450	15,618	44,538	41,884
Gross Profit:	'	'	'	'
Total Gross Profit	4,820	5,075	14,145	13,498
Operating Income (Loss):	'	'	'	'
Total Operating Income	($779)	($1,154)	($2,170)	($3,745)

Segment_Reporting_Revenue_by_G

Segment Reporting (Revenue by Geographical Areas) (Details) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenues:	'	'	'	'
Domestic	$411,817	$354,831	$1,179,417	$739,150
Foreign	20,354	19,680	59,870	57,984
Total Revenues	$432,171	$374,511	$1,239,287	$797,134

Segment_Reporting_Reconciliati

Segment Reporting (Reconciliation of Assets from Segment to Consolidated) (Details) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Segment Reporting, Asset Reconciling Item	'	'
Total Assets	$1,118,482	$1,098,021
Apex	'	'
Segment Reporting, Asset Reconciling Item	'	'
Total Assets	664,284	642,594
Oxford	'	'
Segment Reporting, Asset Reconciling Item	'	'
Total Assets	240,911	231,211
Life Sciences and Healthcare	'	'
Segment Reporting, Asset Reconciling Item	'	'
Total Assets	132,008	139,601
Physician	'	'
Segment Reporting, Asset Reconciling Item	'	'
Total Assets	$81,279	$84,615