Alliance HealthCare Services (AIQ) 10-Q 11 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2015	11-May-15
Document and Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Entity Registrant Name	Alliance HealthCare Services, Inc
Entity Central Index Key	817135
Current Fiscal Year End Date	-19
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		10,748,109

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Current assets:
Cash and cash equivalents	$31,489	$33,033
Accounts receivable, net of allowance for doubtful accounts	64,577	62,503
Deferred income taxes	16,834	16,834
Prepaid expenses	12,441	12,527
Other receivables	2,569	5,686
Total current assets	127,910	130,583
Equipment, at cost	844,596	827,638
Less accumulated depreciation	-685,734	-678,291
Equipment, net	158,862	149,347
Goodwill	86,474	63,864
Other intangible assets, net	138,495	115,930
Deferred financing costs, net	7,790	8,119
Other assets	32,109	33,042
Total assets	551,640	500,885
Current liabilities:
Accounts payable	13,841	12,109
Accrued compensation and related expenses	16,890	19,808
Accrued interest payable	3,132	3,154
Other accrued liabilities	27,863	26,542
Current portion of long-term debt	19,438	15,512
Total current liabilities	81,164	77,125
Long-term debt, net of current portion	514,888	491,777
Other liabilities	6,564	6,623
Deferred income taxes	37,936	36,840
Total liabilities	640,552	612,365
Commitments and contingencies
Stockholders’ deficit:
Common stock	107	107
Treasury stock	-3,138	-3,138
Additional paid-in capital	27,966	27,653
Accumulated comprehensive loss	-479	-351
Accumulated deficit	-192,340	-194,091
Total stockholders’ deficit attributable to Alliance HealthCare Services, Inc.	-167,884	-169,820
Noncontrolling interest	78,972	58,340
Total stockholders’ deficit	-88,912	-111,480
Total liabilities and stockholders’ deficit	$551,640	$500,885

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Income Statement [Abstract]
Revenues	$109,429	$105,365
Costs and expenses:
Cost of revenues, excluding depreciation and amortization	61,886	56,940
Selling, general and administrative expenses	20,955	18,739
Transaction costs	419	2
Severance and related costs	259	133
Impairment charges	76	0
Depreciation expense	11,633	15,795
Amortization expense	2,035	1,952
Interest expense and other, net	6,018	6,238
Other expense (income), net	-359	77
Total costs and expenses	102,922	99,876
Income before income taxes, earnings from unconsolidated investees, and noncontrolling interest	6,507	5,489
Income tax expense	1,572	1,507
Earnings from unconsolidated investees	-1,163	-998
Net income	6,098	4,980
Less: Net income attributable to noncontrolling interest	-4,347	-3,049
Net income attributable to Alliance HealthCare Services, Inc.	1,751	1,931
Comprehensive income, net of taxes:
Net income attributable to Alliance HealthCare Services, Inc.	1,751	1,931
Unrealized gain (loss) on hedging transactions, net of taxes	-128	20
Comprehensive income, net of taxes	$1,623	$1,951
Income per common share attributable to Alliance HealthCare Services, Inc.:
Basic (dollars per share)	$0.16	$0.18
Diluted (dollars per share)	$0.16	$0.18
Weighted-average number of shares of common stock and common stock equivalents:
Basic (shares)	10,714	10,666
Diluted (shares)	10,842	10,890

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Cash Flows (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Operating activities:
Net income	$6,098	$4,980
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for doubtful accounts	438	553
Share-based payment	389	334
Depreciation and amortization	13,668	17,747
Amortization of deferred financing costs	483	478
Accretion of discount on long-term debt	114	111
Adjustment of derivatives to fair value	72	31
Distributions (less) more than undistributed earnings from investees	254	96
Deferred income taxes	1,096	421
Gain on sale of assets	0	141
Impairment charges	76	0
Excess tax benefit from share-based payment arrangements	5	0
Changes in operating assets and liabilities, net of the effects of acquisitions:
Accounts receivable	1,928	1,434
Prepaid expenses	-45	1,919
Other receivables	-2	422
Other assets	1,326	167
Accounts payable	563	-3,604
Accrued compensation and related expenses	-4,066	-8,314
Accrued interest payable	-22	1,463
Income taxes payable	0	6
Other accrued liabilities	-1,597	573
Net cash provided by operating activities	20,778	18,958
Investing activities:
Equipment purchases	-7,565	-5,735
Decrease (increase) in deposits on equipment	-1,836	1,507
Acquisitions, net of cash received	-23,630	0
Proceeds from sale of assets	120	142
Net cash used in investing activities	-32,911	-4,086
Financing activities:
Principal payments on equipment debt	-1,973	-2,866
Principal payments on term loan facility	-6,126	-1,225
Principal payments on revolving loan facility	0	-27,000
Proceeds from revolving loan facility	23,000	16,000
Noncontrolling interest in subsidiaries	-4,313	-3,771
Equity purchase of noncontrolling interest	0	-1,500
Excess tax benefit from share-based payment arrangements	-5	0
Proceeds from shared-based payment arrangements	6	55
Purchase of treasury stock	0	-140
Net cash (used in) provided by financing activities	10,589	-20,447
Net decrease in cash and cash equivalents	-1,544	-5,575
Cash and cash equivalents, beginning of period	33,033	34,702
Cash and cash equivalents, end of period	31,489	29,127
Supplemental disclosure of cash flow information:
Interest paid	5,427	4,338
Income taxes paid, net of refunds	40	46
Supplemental disclosure of non-cash investing and financing activities:
Capital lease obligations related to the purchase of equipment	1,294	0
Unrealized gain (loss) on hedging transactions, net of taxes	-128	20
Equipment purchases in accounts payable	1,225	531
Noncontrolling interest assumed in connection with acquisitions (Note 2)	20,598	0
Adjustment to equity of noncontrolling interest	0	1,700
Debt related to purchase of equipment	3,025	0
Debt related to purchase of deposits on equipment	4,069	0
Debt related to other assets	854	0
Extinguishment of note receivable (Note 2)	$3,071	$0

Basis_of_Presentation_Principl

Basis of Presentation, Principles of Consolidation, and Use of Estimates	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation, Principles of Consolidation, and Use of Estimates	Basis of Presentation, Principles of Consolidation, and Use of Estimates
	Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared by Alliance HealthCare Services, Inc. (the “Company”) in accordance with accounting principles generally accepted in the United States of America and with the instructions to Form 10-Q and Article 10 of Regulation S-X of the Securities and Exchange Commission. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles (“GAAP”) for complete financial statements. In the opinion of management, all adjustments (including normal recurring accruals) considered necessary for a fair presentation have been included. Operating results for the three months ended March 31, 2015 are not necessarily indicative of the results that may be expected for the year ending December 31, 2015. The accompanying unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes to the consolidated financial statements for the year ended December 31, 2014.
	Principles of Consolidation The accompanying unaudited condensed consolidated financial statements of the Company include the assets, liabilities, revenues and expenses of all majority-owned subsidiaries over which the Company exercises control. Intercompany transactions have been eliminated. The Company records noncontrolling interest related to its consolidated subsidiaries which are not wholly owned. Investments in non-consolidated investees are accounted for under the equity method.
	Use of Estimates The preparation of condensed consolidated financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. Actual results could differ from those estimates.

Transactions

Transactions	3 Months Ended
	Mar. 31, 2015
Restructuring and Related Activities [Abstract]
Transactions	Transactions
	Restructuring Plan
	During the three months ended March 31, 2015, the Company recorded $255 related to restructuring charges, of which the Company recorded $55 in Selling, general and administrative expenses, and $200 in Cost of revenues, excluding depreciation and amortization. The Company also recorded $259 in Severance and related costs. During the three months ended March 31, 2014, the Company recorded $1,025 related to restructuring charges, of which the Company recorded $704 in Selling, general and administrative expenses; $133 in Severance and related costs, primarily as a result of the departure of one of its executive officers during the second quarter of 2014; and $188 in Cost of revenues, excluding depreciation and amortization.
	Acquisition of The Pain Center of Arizona
	On February 17, 2015, the Company purchased approximately 59% membership interest in The Pain Center of Arizona ("TPC"), a comprehensive full-time pain management medical practice with 12 locations within the state of Arizona. The acquisition took place in two stages: a purchase of a 60.0% membership interest in TPC by the Company, and a 50.0% membership interest in Medical Practice Innovations, Inc. (“MPI”), followed by a transfer of MPI assets to TPC. The MPI transaction diluted the ownership interests of TPC, with the Company retaining approximately 59% membership interest in TPC. The purchase price consisted of $23,630 in cash, net of $691 cash acquired, and net of extinguishment of $3,071 of related-party notes receivable. The Company financed this acquisition using the revolving line of credit.
	The following table summarizes recognized amounts of identifiable assets acquired and liabilities assumed at the acquisition date:
	Cash received	$	691
	Accounts receivable, net	4,440
	Equipment, net	3,346
	Other assets	416
	Goodwill	22,610
	Identifiable intangible assets	24,600
	Debt	(2,781		)
	Other liabilities	(3,531		)
	Noncontrolling interest	(20,598		)
	Cash consideration paid	$	29,193
	As a result of this acquisition, the Company recorded goodwill of $22,610. In addition, the Company recorded intangible assets of $24,600, of which $13,500 was assigned to physician referral network and $11,100 was assigned to trademarks, which are all being amortized over 20 years. The Company recorded the intangible assets at fair value at the acquisition date, which was estimated using the income approach. A portion of the recorded goodwill and intangible assets is being amortized over 15 years for tax purposes. The fair value of noncontrolling interest related to this transaction was $20,598 as of the acquisition date. To estimate the fair value of noncontrolling interest, the Company used the implied fair value based on the Company's ownership percentage. The results for the three months ended March 31, 2015 included $3,855 of revenue and $271 of net income generated by TPC. The historical results of operations of the business acquired during the three months ended March 31, 2015 are not material, and accordingly, pro forma financial information is not presented.
	The values assigned to the various assets and liabilities acquired in this transaction are preliminary and may be subject to adjustment as the calculation of their respective fair values could be subject to change.
	The agreement includes contingent consideration arrangements, which are based on performance of the 12-month period following the transaction date. The fair value of these contingent consideration arrangements of $1,800 was estimated using probability-adjusted performance estimates as of March 31, 2015.

ShareBased_Payment

Share-Based Payment	3 Months Ended
	Mar. 31, 2015
Share-based Compensation [Abstract]
Share-Based Payment	Share-Based Payment
	The Company has adopted ASC 718, “Compensation—Stock Compensation,” and has elected to follow the alternative transition method as described in ASC 718 for computing its beginning additional paid-in capital pool. In addition, the Company treats the tax deductions from stock options as being realized when they reduce taxes payable in accordance with the principles and timing under the relevant tax law.
	Stock Option Plans and Awards
	In November 1999, the Company adopted an employee stock option plan (as amended and restated, the “1999 Equity Plan”) pursuant to which options and awards with respect to a total of 2,205,000 shares have become available for grant. As of March 31, 2015, a total of 472,391 shares remained available for grant under the 1999 Equity Plan. Options are granted with exercise prices equal to the fair value of the Company’s common stock at the date of grant. All options have 10-year terms. Options granted after January 1, 2008 are typically time based and vest in equal traunches over three or four years. During the year ended December 31, 2014 and the three months ended March 31, 2015 there were no options in which vesting was accelerated. Prior to January 1, 2008, stock options granted under the 1999 Equity Plan to employees were always time options which vest 5% in the first year, 20% in the second year and 25% in years three through five.
	The Company uses the Black-Scholes option pricing model to value the compensation expense associated with share-based payment awards. The fair value of each option award is estimated on the date of grant using the Black-Scholes option pricing model using the assumptions noted in the table below. In addition, forfeitures are estimated when recognizing compensation expense and the estimate of forfeitures will be adjusted over the requisite service period to the extent that actual forfeitures differ, or are expected to differ, from such estimates. Changes in estimated forfeitures will be recognized through a cumulative catch-up adjustment in the period of change and will also impact the amount of compensation expense to be recognized in future periods.
	The following weighted average assumptions were used in the estimated grant date fair value calculations for stock option awards:
		Three months ended March 31,
		2014		2015
	Risk free interest rate	1.83	%	1.65	%
	Expected dividend yield	—	%	—	%
	Expected stock price volatility	66.3	%	65.2	%
	Average expected life (in years)	6		6
	The Company calculates its stock price volatility and average expected life based on its own historical data. The risk free interest rates are based on the United States Treasury yield curve in effect at the time of grant for periods corresponding with the expected life of the option or award.
	The following table summarizes the Company’s stock option activity:
		Number of		Weighted-		Weighted-	Aggregate
		Shares		Average		Average	Intrinsic
				Exercise Price		Remaining	Value
						Contractual
						Term
	Outstanding at January 1, 2015	633,898		$	21.39
	Granted	83,514		23.91
	Exercised	(1,000	)	6.2
	Canceled	(23,500	)	61.75
	Outstanding at March 31, 2015	692,912		$	20.36	6.28	$	4,510
	Vested and expected to vest in the future at March 31, 2015	666,254		$	20.21	6.2	$	4,487
	Exercisable at March 31, 2015	473,363		$	18.39	5.34	$	4,180
	The weighted average grant date fair value of options granted during the three months ended March 31, 2014 and 2015 was $17.56 per share and $14.25 per share, respectively. Total stock options exercised was 1,000 during the three months ended March 31, 2015. There were 7,667 options exercised during the three months ended March 31, 2014.
	The following table summarizes the Company’s unvested stock option activity:
		Shares		Weighted-Average
				Grant-Date
				Fair Value
	Unvested at January 1, 2015	197,899		$	12.13
	Granted	83,514		14.25
	Vested	(61,864	)	6.02
	Canceled	—		—
	Unvested at March 31, 2015	219,549		$	14.69
	At March 31, 2015, the total unrecognized fair value share-based payment related to unvested stock options granted to employees was $2,353, which is expected to be recognized over a remaining weighted-average period of 2.30 years. The valuation model applied in this calculation utilizes highly subjective assumptions that could potentially change over time, including the expected forfeiture rate and performance targets. Therefore, the amount of unrecognized share-based payment noted above does not necessarily represent the value that will ultimately be realized by the Company in the consolidated statements of operations and comprehensive income. The total fair value of shares vested during the three months ended March 31, 2014 and 2015 was $360 and $372, respectively.
	Stock Awards
	The 1999 Equity Plan, as amended and restated, permits the award of restricted stock, restricted stock units, stock bonus awards and performance-based awards. During 2012, awards to certain employees either cliff vested after one year, or vest annually in 33.3% increments over three years. During 2013, awards to certain employees vested immediately upon the date of grant, or cliff vest after one year provided that the employee remains continuously employed through the issuance date. The Company grants restricted stock awards to non-employee directors of the Company who are unaffiliated with Oaktree Capital Management, LLC (“Oaktree”) and MTS Health Investors, LLC (“MTS”) (“unaffiliated directors”). These awards to unaffiliated directors cliff vest after one year based on the unaffiliated directors’ continued service with the Company through that date.
	For the three months ended March 31, 2014 and 2015, the Company recorded share-based payment related to restricted stock awards of $92 and $172, respectively. There were no shares of restricted stock granted during the three months ended March 31, 2014.
	Restricted stock units ("RSU") totaling 25,000 were granted to the Company's Chief Executive Officer in the third quarter of 2014, which vest based upon achieving certain market performance conditions. Specifically, the Company's closing stock price per common share must equal or exceed a value of $40.00 per share for 10 consecutive days between the dates of January 1, 2015 and April 21, 2017. If these conditions are not achieved before April 21, 2017, these RSUs will expire. In accordance with ASC 718, expense related to restricted stock units that vest based on achieving a market condition should not be recognized until the derived vesting period has been met, and at such time the derived vesting period becomes the requisite service period. Since the market condition has not been met, and is currently not probable of being met based on the current market condition, the Company has not recognized any expense related to these RSUs.
	The following table summarizes the Company’s restricted stock activity:
		Shares		Weighted-Average
				Grant-Date
				Fair Value
	Unvested at January 1, 2015	32,959		$	20.99
	Granted to employees	—		—
	Granted to non-employee directors	—		—
	Vested	—		—
	Canceled	—		—
	Unvested at March 31, 2015	32,959		$	20.99
	At March 31, 2015, there is no unrecognized fair value share-based payment expense related to restricted stock awards granted to employees. At March 31, 2015, the total unrecognized fair value share-based payment expense related to the restricted stock awards granted to unaffiliated directors was $517, which is expected to be recognized over a remaining weighted-average period of 0.75 years.
	Directors' Compensation Program
	In 2014 and 2015, under the compensation program for non-employee directors, non-employee directors earn an annual fee of $40 for their services as directors. In addition, each Unaffiliated Director received a restricted stock unit award on December 31 for the number of shares of our Common Stock having a value equal to $140, using the average share price of our Common Stock over the 15-day period preceding the grant date. These restricted stock unit awards vest on the first anniversary of their respective date of grant contingent upon the Unaffiliated Director's continued service to the Company through that date. In addition to the annual fee for all non-employee directors, each Affiliated Director receives additional annual cash compensation of $140, paid in one annual installment, for serving on the Board during 2014 and 2015.
	Beginning October 1, 2013, the Chairman of the Board, Mr. Buckelew, is entitled to restricted stock units having a value equal to $138 as compensation for a service period of one year, for the 24 month period following his resignation as the Company's CEO. Also during 2014, non-employee directors who served as members of our Audit Committee received an additional $15, and the non-employee director who served as Chairman of our Audit Committee received an additional $30. In 2014, non-employee directors who served as members of our Nominating Committee, Compensation Committee and Strategy & Finance Committee received an additional $5, and the non-employee director who served as Chairman of our Strategy and Finance Committee received an additional $25. In 2014, non-employee directors were reimbursed for travel expenses related to their Board service.

Recent_Accounting_Pronouncemen

Recent Accounting Pronouncements	3 Months Ended
	Mar. 31, 2015
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements
	Revenue Recognition In May 2014, the FASB issued ASU number 2014-09, “Revenue from Contracts with Customers (Topic 606)" — to clarify and converge the revenue recognition principles under U.S. GAAP and IFRSs and to develop guidance that would streamline and enhance revenue recognition requirements while also providing a more robust framework for addressing revenue issues. ASU 2014-09 outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most current revenue recognition guidance, including industry-specific guidance. Key provisions of the ASU involve a 5-step model specific to recognizing revenue derived from customer contracts. In addition, ASU 2014-09 provides implementation guidance on several other important topics, including the accounting for certain revenue-related costs. The adoption of ASU 2014-09 is effective for publicly traded business entities for annual reporting periods beginning after December 15, 2017, including interim reporting periods within that reporting period. Earlier application is not permitted. The Company is assessing the impact, if any, that the adoption of ASU 2014-09 may have on the Company's results of operations, cash flows, or financial position.
	Going Concern In August 2014, the FASB issued ASU number 2014-15, "Presentation of Financial Statements—Going Concern (Subtopic 205-40)". Under U.S. GAAP, a going concern is presumed unless and until an entity’s liquidation becomes imminent. When an entity’s liquidation becomes imminent, financial statements should be prepared under the liquidation basis of accounting in accordance with Subtopic 205-30, "Presentation of Financial Statements—Liquidation Basis of Accounting." However, there may be conditions or events that raise substantial doubt about an entity’s ability to continue as a going concern, even if liquidation is not imminent. In those situations, financial statements should continue to be prepared under the going concern basis of accounting. ASU 2014-15 provides guidance about management’s responsibility to evaluate whether there is substantial doubt about an entity’s ability to continue as a going concern and to determine whether to disclose information about relevant conditions and events. ASU 2014-15 is effective for annual periods ending after December 15, 2016, and for annual periods and interim periods thereafter. Early application is permitted. The Company is assessing the impact, if any, that the adoption of ASU 2014-15 may have on the Company's results of operations, cash flows, or financial position.

Fair_Value_of_Financial_Instru

Fair Value of Financial Instruments	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments
	The Company used the following methods and assumptions in estimating fair value disclosure for financial instruments:
	Cash and cash equivalents The carrying amounts reported in the balance sheets approximate fair value due to the short-term maturity or variable rates of these instruments.
	Debt The carrying amount of fixed and variable-rate borrowings at March 31, 2015 approximates fair value estimated based on current market rates and credit spreads for similar debt instruments.
	Derivative instruments Fair value was determined based on the income approach and standard valuation techniques to convert future amounts to a single present amount and approximates the net gains and losses that would have been realized if the contracts had been settled at each period-end.
	The estimated fair values of the Company’s financial instruments are as follows:
		December 31, 2014				31-Mar-15
		Carrying		Fair		Carrying		Fair
		Value		Value		Value		Value
	Cash and cash equivalents	$	33,033	$	33,033	$	31,489	$	31,489
	Fixed-rate debt	13,015		13,878		23,814		24,070
	Variable-rate debt	494,274		494,354		510,512		509,577
	Contingent consideration related to acquisition	—		—		1,800		1,800
	Derivative instruments - asset position	228		228		48		48
	Derivative instruments - liability position	46		46		56		56
	ASC 820, “Fair Value Measurement,” applies to all assets and liabilities that are being measured and reported at fair value on a recurring basis. ASC 820 requires disclosure that establishes a framework for measuring fair value in generally accepted accounting principles by establishing a hierarchy for ranking the quality and reliability of the information used to determine fair values. The statement requires that assets and liabilities carried at fair value will be classified and disclosed in one of the following three categories:
		Level 1	Quoted market prices in active markets for identical assets or liabilities.
		Level 2	Observable market based inputs or unobservable inputs, including identical securities in inactive markets or similar securities in active markets, that are corroborated by market data.
		Level 3	Unobservable inputs that are not corroborated by market data.
	None of the Company’s instruments have transferred from one level to another.
	The following table summarizes the valuation of the Company’s financial instruments that are reported at fair value on a recurring basis by the above ASC 820 pricing levels as of December 31, 2014:
		Total		Quoted market		Significant other		Significant
				prices in active		observable  inputs		unobservable
				markets (Level 1)		(Level 2)		inputs (Level 3)
	Cash and cash equivalents	$	33,033	$	33,033	$	—	$	—
	Interest rate contracts - asset position	228				228
	Interest rate contracts - liability position	46		—		46		—
	The following table summarizes the valuation of the Company’s financial instruments that are reported at fair value on a recurring basis by the above ASC 820 pricing levels as of March 31, 2015:
		Total		Quoted market		Significant other		Significant
				prices in active		observable  inputs		unobservable
				markets (Level 1)		(Level 2)		inputs (Level 3)
	Cash and cash equivalents	$	31,489	$	31,489	$	—	$	—
	Interest rate contracts - asset position	48		—		48		—
	Interest rate contracts - liability position	56		—		56		—
	The Company’s derivative instruments are primarily pay-fixed, receive-variable interest rate swaps and caps based on the LIBOR swap rate. The Company has elected to use the income approach to value these derivatives, using observable Level 2 market expectations at measurement date and standard valuation techniques to convert future amounts to a single present amount assuming that participants are motivated, but not compelled to transact. Level 2 inputs for interest rate swap and cap valuations are limited to quoted prices for similar assets or liabilities in active markets (specifically futures contracts on LIBOR for the first two years) and inputs other than quoted prices that are observable for the asset or liability (specifically LIBOR cash and swap rates at commonly quoted intervals and implied volatilities for options). ASC 820 states that the fair value measurement of an asset or liability must reflect the nonperformance risk of the entity and the counterparty. Therefore, the impact of the counterparty’s creditworthiness and the Company’s creditworthiness has also been factored into the fair value measurement of the derivative instruments. For additional information please see Note 9 of the Notes to the Condensed Consolidated Financial Statements.

Goodwill_and_Intangible_Assets

Goodwill and Intangible Assets	3 Months Ended
	Mar. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Intangible Assets	Goodwill and Intangible Assets
	Changes in the carrying amount of goodwill are as follows:
	Balance at January 1, 2014	$	56,975
	Goodwill acquired during the period	6,889
	Impairment charges	—
	Adjustments to goodwill during the period	—
	Balance at December 31, 2014	63,864
	Goodwill acquired during the period	22,610
	Impairment charges	—
	Adjustments to goodwill during the period	—
	Balance at March 31, 2015	$	86,474
	Gross goodwill	$	260,718
	Accumulated impairment charges	(174,244		)
	Balance at March 31, 2015	$	86,474
	Intangible assets consisted of the following:
		31-Dec-14								31-Mar-15
		Gross Carrying			Accumulated			Intangible		Gross Carrying		Accumulated			Intangible
		Amount			Amortization			Assets, net		Amount		Amortization			Assets, net
	Amortizing intangible assets:
	Customer contracts	$	162,089		$	(93,617	)	$	68,472	$	175,589	$	(95,440	)	$	80,149
	Other	26,241			(21,758		)	4,483		37,341		(21,970		)	15,371
	Total amortizing intangible assets	$	188,330		$	(115,375	)	$	72,955	$	212,930	$	(117,410	)	$	95,520
	Intangible assets not subject to amortization							42,975							42,975
	Total other intangible assets							$	115,930						$	138,495
	In 2015, the Company intends to perform an annual impairment test in the fourth quarter for goodwill and indefinite life intangible assets based on the financial information as of September 30, absent of other events occurring or changes in circumstances that would more likely than not reduce the fair value of a reporting unit below its carrying amount. The Company compares the fair value of its reporting units to its carrying amount to determine if there is potential impairment. The fair value of the reporting unit is determined by an income approach and a market capitalization approach. Significant management judgment is required in the forecasts of future operating results that are used in the income approach. The estimates that the Company has used are consistent with the plans and estimates that it uses to manage its business. The Company bases its fair value estimates on forecasted revenue and operating costs which include a number of factors including, but not limited to, securing new customers, retention of existing customers, growth in imaging and radiation oncology revenues and the impact of continued cost savings initiatives. However, it is possible that plans and estimates may change. Based on financial information as of March 31, 2015, impairment testing was not required during the three months ended March 31, 2015. Although the Company concluded that no impairment was present in its intangible assets in the three months of 2015, the Company intends to test its Goodwill and other intangibles assets for impairment during the fourth quarter of 2015, as described above.
	The Company uses the estimated useful life to amortize customer contracts, which is a weighted-average of 15 years. Other intangible assets subject to amortization are estimated to have a weighted-average useful life of six years. Amortization expense for intangible assets subject to amortization was $1,952 and $2,035 for the quarters ended March 31, 2014 and 2015, respectively. The intangible assets not subject to amortization represent certificates of need and regulatory authority rights which have indefinite useful lives.
	Estimated annual amortization expense for each of the fiscal years ending December 31, is presented below:
	2015	$	8,599
	2016	7,904
	2017	7,466
	2018	7,105
	2019	6,621
	Thereafter	59,861

Other_Accrued_Liabilities

Other Accrued Liabilities	3 Months Ended
	Mar. 31, 2015
Other Accrued Liabilities [Abstract]
Other Accrued Liabilities	Other Accrued Liabilities
	Other accrued liabilities consisted of the following:
		31-Dec-14		31-Mar-15
	Accrued systems rental and maintenance costs	$	1,586	$	2,105
	Accrued site rental fees	992		919
	Accrued property and sales taxes payable	9,276		9,591
	Accrued self-insurance expense	2,276		2,492
	Deferred gain on sale of equipment	312		312
	Other accrued expenses	12,100		12,444
	Total	$	26,542	$	27,863

LongTerm_Debt_and_Senior_Subor

Long-Term Debt and Senior Subordinated Credit Facility	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Long-Term Debt and Senior Subordinated Credit Facility	Long-Term Debt and Senior Subordinated Credit Facility
	Long-term debt consisted of the following:
		December 31,			31-Mar-15
		2014
	Term loan facility	$	482,825		$	476,699
	Discount on term loan facility	(2,156		)	(2,042		)
	Revolving credit facility	2,000			25,000
	Equipment debt	24,620			34,669
	Long-term debt, including current portion	507,289			534,326
	Less current portion	15,512			19,438
	Long-term debt	$	491,777		$	514,888
	Senior Secured Term Loan Refinancing
	On June 3, 2013, the Company replaced its existing credit facility with a new senior secured credit agreement with Credit Suisse AG, Cayman Islands Branch, as administrative agent, and the other lenders party thereto (the “Credit Agreement”). The Credit Agreement consists of (i) a $340,000, six-year term loan facility, (ii) a $50,000, five-year revolving loan facility, including a $20,000 sublimit for letters of credit, (iii) uncommitted incremental loan facilities of $100,000 of revolving or term loans, plus an additional amount if our pro forma leverage ratio is less than or equal to 3.25, subject to receipt of lender commitments and satisfaction of specified conditions, and (iv) an $80,000 delayed draw term loan facility, which was required to be drawn within thirty days of June 3, 2013 and used for the redemption of $190,000 in aggregate principal amount of the Company's 8% Senior Notes.
	On July 3, 2013 the delayed draw term loan facility was utilized, of which the proceeds were used to redeem $80,000 in aggregate principal amount of the Company's outstanding 8% Senior Notes that were originally issued in December 2009 as a cash tender offer for any and all of its outstanding 71/4% Notes originally issued in December of 2004. The delayed draw term loan facility converted into, and matched the terms of, the new $340,000 term loan facility.
	Borrowings under the Credit Agreement bear interest through maturity at a variable rate based upon, at the Company's option, either the London interbank offered rate ("LIBOR") or the base rate (which is the highest of the administrative agent’s prime rate, one-half of 1.00% in excess of the overnight federal funds rate, and 1.00% in excess of the one-month LIBOR rate), plus, in each case, an applicable margin. With respect to the term loan facilities, the applicable margin for LIBOR loans is 3.25% per annum, and with respect to the revolving loan facilities, the applicable margin for LIBOR loans ranges, based on the applicable leverage ratio, from 3.00% to 3.25% per annum, in each case, with a LIBOR floor of 1.00%. The applicable margin for base rate loans under the term loan facilities is 2.25% per annum and under the revolving loan facility ranges, based on the applicable leverage ratio, from 2.00% to 2.25% per annum. Prior to the refinancing of the term loan facilities, the applicable margin for base rate loans was 4.25% per annum and the applicable margin for revolving loans was 5.25% per annum, with a LIBOR floor of 2.00%. The Company is required to pay a commitment fee which ranges, based on the applicable leverage ratio, from 0.375% to 0.50% per annum on the undrawn portion available under the revolving loan facility and variable per annum fees with respect to outstanding letters of credit.
	During the first five and three-quarter years after the closing date, and including the full amount of the delayed draw term loan facility, the Company will be required to make quarterly amortization payments of the term loans in the amount of $1,050. The Company is also required to make mandatory prepayments of term loans under the Credit Agreement, subject to specified exceptions, from excess cash flow (as defined in the Credit Agreement), and with the proceeds of asset sales, debt issuances and specified other events.
	Obligations under the Credit Agreement are guaranteed by substantially all the Company's direct and indirect domestic subsidiaries. The obligations under the Credit Agreement and the guarantees are secured by a lien on substantially all tangible and intangible property, and by a pledge of all of the shares of stock and limited liability company interests of the Company's direct and indirect domestic subsidiaries, of which the Company now owns or later acquires more than a 50% interest, subject to limited exceptions.
	In addition to other covenants, the Credit Agreement places limits on the ability of the Company and its subsidiaries to declare dividends or redeem or repurchase capital stock, prepay, redeem or purchase debt, incur liens and engage in sale-leaseback transactions, make loans and investments, incur additional indebtedness, amend or otherwise alter debt and other material agreements, engage in mergers, acquisitions and asset sales, transact with affiliates and alter the business conducted by the Company and its subsidiaries.
	The Credit Agreement also contains a leverage ratio covenant requiring the Company to maintain a maximum ratio of consolidated total debt to consolidated adjusted EBITDA expense that ranges from 4.95 to 1.00 to 4.30 to 1.00. For the quarter ended March 31, 2015, the Credit Agreement required a maximum leverage ratio of not more than 4.85 to 1.00. The Credit Agreement eliminated the interest coverage ratio covenant which the Company was subject to maintain prior to the refinancing. Failure to comply with the covenants in the Credit Agreement could permit the lenders under the Credit Agreement to declare all amounts borrowed under the Credit Agreement, together with accrued interest and fees, to be immediately due and payable, and to terminate all commitments under the Credit Agreement.
	On October 11, 2013, the Company entered into an amendment to the Credit Agreement with Credit Suisse AG, Cayman Islands Branch, as administrative agent, and the other lenders party thereto (the “First Amendment”). Pursuant to the First Amendment, the Company raised $70,000 in incremental term loan commitments to repurchase the remaining Notes. On December 2, 2013, the Company borrowed $70,000 of incremental term loans, and with such proceeds plus borrowings under its revolving line of credit and cash on hand, completed the redemption of all of its outstanding Notes on December 4, 2013.
	The incremental term loan was funded at 99.0% of principal amount and will mature on the same date as the existing term loan in June 2019. The incremental term loan will be converted to match all the terms of existing term loans upon funding in December. Interest on the incremental term loan will be calculated, at the Company's option, at a base rate plus a 2.25% margin or LIBOR plus a 3.25% margin, subject to a 1.00% LIBOR floor.
	As of March 31, 2015, there was $476,699 outstanding under the new term loan facility and $25,000 borrowings under the new revolving credit facility. As of March 31, 2015, the Company’s ratio of consolidated total debt to Consolidated Adjusted EBITDA calculated pursuant to the Credit Agreement was 3.75 to 1.00.
	During the first five and one half years after the closing date for the incremental term loan, the quarterly amortization payments of all term loans under the credit facility has increased to $1,225 from the previous amount of $1,050.
	At March 31, 2015, the increase in the Company's current portion of long-term debt is primarily due to borrowings for the recent purchase of TPC and ongoing construction and equipment expenditures for its oncology division's joint venture with the Medical University of South Carolina ("MUSC"). Debt related to TPC was issued through the Company's revolving line of credit while debt related to MUSC has been funded through a line of credit exclusive of the Company's revolving line of credit, and will be converted to notes as phases of the project are completed.
	The Company's obligations under the incremental term loans are guaranteed by substantially all of the Company’s direct and indirect domestic subsidiaries. The obligations under the incremental term loan and the guarantees are secured by a lien on substantially all of the Company’s tangible and intangible property, and by a pledge of all of the shares of stock and limited liability company interests of the Company’s direct and indirect domestic subsidiaries, of which the Company now owns or later acquires more than a 50% interest, subject to limited exceptions.

Derivatives

Derivatives

3 Months Ended

Mar. 31, 2015

Summary of Derivative Instruments [Abstract]

Derivatives

Derivatives

The Company accounts for derivative instruments and hedging activities in accordance with the provisions of ASC 815, “Derivatives and Hedging.” Management generally designates derivatives in a hedge relationship with the identified exposure on the date the Company enters into a derivative contract, as disclosed below. The Company has only executed derivative instruments that are economic hedges of exposures that can qualify in hedge relationships under ASC 815. The Company formally documents all relationships between hedging instruments and hedged items, as well as the risk-management objective and strategy for undertaking various hedge transactions. In this documentation, the Company specifically identifies the firm commitment or forecasted transaction that has been designated as a hedged item and states how the hedging instrument is expected to hedge the risks related to the hedged item. The Company formally assesses effectiveness of its hedging relationships, both at the hedge inception and on an ongoing basis, then measures and records ineffectiveness. The Company would discontinue hedge accounting prospectively (i) if it is determined that the derivative is no longer effective in offsetting change in the cash flows of a hedged item, (ii) when the derivative expires or is sold, terminated or exercised, (iii) because it is probable that the forecasted transaction will not occur, or (iv) if management determines that designation of the derivative as a hedge instrument is no longer appropriate. The Company’s derivatives are recorded on the balance sheet at their fair value. For additional information please see Note 5 of the Notes to the Condensed Consolidated Financial Statements. For derivatives accounted for as cash flow hedges, any effective unrealized gains or losses on fair value are included in comprehensive income (loss), net of tax, and any ineffective gains or losses are recognized in income immediately. Amounts recorded in comprehensive income are reclassified to earnings when the hedged item impacts earnings.

Cash Flow Hedges

Interest Rate Cash Flow Hedges

The Company has entered into multiple interest rate swap and cap agreements to hedge the future cash interest payments on portions of its variable rate bank debt. For the three months ended March 31, 2014 and 2015, the Company had interest rate swap and cap agreements to hedge approximately $259,320 and $257,902 of its variable rate bank debt, respectively, or 50.4% and 48.3% of total debt, respectively. Over the next twelve months, the Company expects to reclassify $195 from accumulated comprehensive loss to interest expense and other, net.

In the first quarter of 2010, the Company entered into three interest rate cap agreements, in accordance with Company policy, to avoid unplanned volatility in the income statement due to changes in the LIBOR interest rate environment. The interest rate cap agreements matured in February 2014, had a total notional amount of $150,000, and were de-designated as cash flow hedges associated with the Company’s variable rate bank debt in the fourth quarter of 2013.

In the second quarter of 2011, the Company acquired two interest rate swap agreements (the “USR Swaps”) as part of the acquisition of US Radiosurgery, LLC ("USR"). One of the USR Swaps, which matures in October 2015, had a notional amount of $610 as of March 31, 2015. Under the terms of this agreement, the Company receives one-month LIBOR and pays a fixed rate of 5.71%. The net effect of the hedge is to record interest expense at a fixed rate of 8.71%, as the underlying debt incurred interest based on one-month LIBOR plus 3.00%. The other USR Swap matured in April 2014. As a result of the acquisition of USR, the USR Swap was de-designated, hedge accounting was terminated and all further changes in the fair market value of the swap is being recorded in interest expense and other, net.

In the fourth quarter of 2012, the Company entered into an interest rate swap agreement in connection with equipment financing. The swap, which matures in December 2017, had a notional amount of $2,976 as of March 31, 2015. Under the terms of this agreement, the Company receives one-month LIBOR plus 2.50% and pays a fixed rate of 3.75%. The net effect of the hedge is to convert interest expense to a fixed rate of 3.75%, as the underlying debt incurred interest based on one-month LIBOR plus 2.50%.

In the first quarter of 2013, the Company entered into an interest rate swap agreement in connection with equipment financing. The swap, which matures in April 2018, had a notional amount of $2,710 as of March 31, 2015. Under the terms of this agreement, the Company receives one-month LIBOR plus 2.00% and pays a fixed rate of 2.873%. The net effect of the hedge is to convert interest expense to a fixed rate of 2.873%, as the underlying debt incurred interest based on one-month LIBOR plus 2.00%.

In the fourth quarter of 2013, the Company entered into five interest rate cap agreements ("2013 Caps"), in accordance with Company policy, to avoid unplanned volatility in the income statement due to changes in the LIBOR interest rate environment. The 2013 Caps, which mature in December 2016, had a notional amount of $250,000 and were designated as cash flow hedges of future cash interest payments associated with a portion of the Company’s variable rate bank debt. Under these arrangements, the Company has purchased a cap on LIBOR at 2.50%. The Company paid $815 to enter into the caps, which is being amortized through interest expense and other, net over the life of the agreements.

In the fourth quarter of 2014, the Company entered into an interest rate swap agreement in connection with equipment financing. The swap, which matures in November 2019, had a notional amount of $1,605 as of March 31, 2015. Under the terms of this agreement, the Company receives one-month LIBOR and pays a fixed rate of 1.34%. The net effect of the hedge is to convert interest expense to a fixed rate of 1.34%, as the underlying debt incurred interest based on one-month LIBOR.

The Effect of Designated Derivative Instruments on the Statement of Operations

For the Three Months Ended March 31, 2014

Derivatives in Cash

Amount of Gain (Loss)

Location of Gain

Amount of Gain (Loss)

Location of Gain

Amount of Gain (Loss)

Flow Hedging

Recognized in OCI on

(Loss)

Reclassified from

(Loss) Recognized in

Recognized in Income

Relationships

Derivatives (Effective

Reclassified from

Accumulated OCI into

Income on Derivatives

on Derivatives

Portion)

Accumulated OCI into

Income (Effective

(Ineffective Portion)

(Ineffective Portion)

Income (Effective

Portion)

Portion)

Interest rate contracts

$

(103

)

Interest expense and other, net

$

(134

)

Interest expense and other, net

$

(2

)

The Effect of Designated Derivative Instruments on the Statement of Operations

For the Three Months Ended March 31, 2015

Derivatives in Cash

Amount of Gain (Loss)

Location of Gain

Amount of Gain (Loss)

Location of Gain

Amount of Gain (Loss)

Flow Hedging

Recognized in OCI on

(Loss)

Reclassified from

(Loss) Recognized in

Recognized in Income

Relationships

Derivatives (Effective

Reclassified from

Accumulated OCI into

Income on Derivatives

on Derivatives

Portion)

Accumulated OCI into

Income (Effective

(Ineffective Portion)

(Ineffective Portion)

Income (Effective

Portion)

Portion)

Interest rate contracts

$

(189

)

Interest expense and other, net

$

11

Interest expense and other, net

$

1

The Effect of Non-Designated Derivative Instruments on the Statements of Operations for the three months ended March 31, 2014 and 2015 was immaterial.

Income_Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes
	For the three months ended March 31, 2014, the Company recorded income tax expense of $1,507, or 43.8%, of the Company’s pretax income. For the three months ended March 31, 2015, the Company recorded income tax expense of $1,572, or 47.3%, of the Company’s pretax income. The Company’s effective tax rate for the three months ended March 31, 2015 differed from the federal statutory rate principally as a result of state income taxes and permanent non-deductible tax items, including share-based payments, unrecognized tax benefits and other permanent differences.
	As of March 31, 2015, the Company has provided a liability for $285 of unrecognized tax benefits related to various federal and state income tax matters. The tax-effected amount that would reduce the Company’s effective income tax rate if recognized is $243.
	The Company recognizes accrued interest and penalties related to unrecognized tax benefits in income tax expense. As of March 31, 2015, the Company had approximately $14 in accrued interest and penalties related to unrecognized tax benefits.
	The Company is subject to United States federal income tax as well as income tax of multiple state tax jurisdictions. The Company is currently open to audit under the statute of limitations by the Internal Revenue Service for the years ended December 31, 2011 through 2014. The Company’s and its subsidiaries’ state income tax returns are open to audit under the applicable statutes of limitations for the years ended December 31, 2010 through 2014. The Company does not anticipate a significant change to the total amount of unrecognized tax benefits within the next 12 months.

Earnings_Per_Common_Share

Earnings Per Common Share	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Earnings per Common Share	Earnings Per Common Share
	Basic net income per share is computed utilizing the two-class method and is calculated based on the weighted-average number of common shares outstanding during the periods presented, excluding nonvested restricted stock units which do not contain nonforfeitable rights to dividend and dividend equivalents.
	Diluted net income per share is computed using the weighted-average number of common and common equivalent shares outstanding during the periods utilizing the two-class method for stock options, nonvested restricted stock and nonvested restricted stock units. Potentially dilutive securities are not considered in the calculation of net loss per share as their impact would be anti-dilutive.
	The following table sets forth the computation of basic and diluted earnings per share:
		Quarter Ended
		March 31,
		2014		2015
	Numerator:
	Net income attributable to Alliance HealthCare Services, Inc.	$	1,931	$	1,751
	Denominator:
	Weighted-average shares-basic	10,666		10,714
	Effect of dilutive securities:
	Employee stock options	224		128
	Weighted-average shares-diluted	10,890		10,842
	Income per common share attributable to Alliance HealthCare Services, Inc.:
	Basic	$	0.18	$	0.16
	Diluted	$	0.18	$	0.16
	Stock options excluded from the computation of diluted per share amounts:
	Weighted-average shares for which the exercise price exceeds average market price of common stock	135		310
	Average exercise price per share that exceeds average market price of common stock	$	44.29	$	32.2

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies
	In the normal course of business, the Company has made certain guarantees and indemnities, under which it may be required to make payments to a guaranteed or indemnified party, in relation to certain transactions. The Company indemnifies other parties, including customers, lessors, and parties to other transactions with the Company, with respect to certain matters. The Company has agreed to hold the other party harmless against losses arising from certain events as defined within the particular contract, which may include, for example, litigation or claims arising from a breach of representations or covenants. In addition, the Company has entered into indemnification agreements with its executive officers and directors and the Company's bylaws contain similar indemnification obligations. Under these arrangements, the Company is obligated to indemnify, to the fullest extent permitted under applicable law, its current or former officers and directors for various amounts incurred with respect to actions, suits or proceedings in which they were made, or threatened to be made, a party as a result of acting as an officer or director.
	It is not possible to determine the maximum potential amount under these indemnification agreements due to the limited history of prior indemnification claims and the unique facts and circumstances involved in each particular agreement. Historically, payments made related to these indemnifications have been immaterial. At March 31, 2015, the Company has determined that no liability is necessary related to these guarantees and indemnities.
	In June 2012, Pacific Coast Cardiology (“PCC”) d/b/a Pacific Coast Imaging, Emanuel Shaoulian, MD, Inc., and Michael M. Radin, MD, Inc. filed a lawsuit in California state court against the Company and other defendants. The complaint asserted a number of claims related to the Company’s decision not to purchase PCC in 2010, and also separately sought a determination regarding an amount the Company contended was owed to it by PCC pursuant to a previous contractual arrangement. In July 2014, the parties entered into a settlement agreement for an amount that is not material to the Company's financial position, results or operations or cash flows, for which the Company previously recorded an accrual. The court approved the settlement on August 11, 2014.
	On November 9, 2012, U.S. Radiosurgery, LLC (“USR”) a subsidiary of the Company, received a grand jury subpoena issued by the United States Attorney's Office for the Middle District of Tennessee seeking documents related to USR and its financial relationships with physicians and other healthcare providers. The federal government has informed the Company that this matter has been closed.
	On March 27, 2013, the Company was served with a lawsuit filed in U.S. District Court for the Northern District of Mississippi by Superior MRI Services, Inc.  The plaintiff is an alleged successor in interest to a former local competitor, P&L Contracting, Inc. Plaintiff alleges the Company disregarded Mississippi Certificate of Need ("CON") rules and regulations by operating without obtaining the appropriate authority, and is seeking in excess of $1,000 in damages as well as requesting injunctive relief.  In January of 2014, the District Court dismissed plaintiff’s complaint on a number of procedural and substantive grounds. The plaintiff subsequently appealed the District Court’s ruling to the Fifth Circuit Court of Appeals. On February 18, 2015, the Fifth Circuit Court of Appeals affirmed the District Court’s dismissal, thereby, effectively concluding this case in Alliance’s favor.
	On June 14, 2013, Alliance Oncology, LLC, a subsidiary of the Company, filed a complaint against Harvard Vanguard Medical Associates, Inc. (“HVMA”) in the United States District Court for the District of Massachusetts, including several claims seeking damages resulting from HVMA’s early termination of a long-term services agreement between the two companies. HVMA filed an answer to Alliance Oncology’s complaint on August 27, 2013. Without specifying its alleged damages, HVMA also asserted several counterclaims in its answer. The Company filed its answer to HVMA’s counterclaims on October 4, 2013, and intends to vigorously defend against the claims asserted. The Company has not recorded an expense related to any potential damages in connection with this matter because any potential loss is not probable or reasonably estimable at this time.
	The Company from time to time is involved in routine litigation and regulatory matters incidental to the conduct of its business. The Company believes that resolution of such matters will not have a material adverse effect on its consolidated results of operations, financial position, or cash flows.

RelatedParty_Transactions

Related-Party Transactions	3 Months Ended
	Mar. 31, 2015
Related Party Transactions [Abstract]
Related-Party Transactions	Related-Party Transactions
	On April 16, 2007, Oaktree and MTS purchased 4,900,301 shares of the Company’s common stock. Upon completion of the transaction, Oaktree and MTS owned in the aggregate approximately 49.7% of the outstanding shares of common stock of the Company. At March 31, 2015, Oaktree and MTS owned in the aggregate approximately 50.7% of the outstanding shares of common stock of the Company. The Company does not pay management fees to Oaktree and MTS for their financial advisory services to the Company.
	Revenues from management agreements with unconsolidated equity investees were $2,321 and $2,378 during the quarters ended March 31, 2014 and 2015, respectively. The Company provides services as part of its ongoing operations for and on behalf of the unconsolidated equity investees, which are included in the management agreement revenue, who reimburse the Company for the actual amount of the expenses incurred. The Company records the expenses as cost of revenues and the reimbursement as revenues in its condensed consolidated statements of operations and comprehensive income. For the quarters ended March 31, 2014 and 2015, the amounts of the revenues and expenses were $1,904 and $1,947, respectively.
	On June 3, 2013, the Company replaced its existing credit facility with a new senior secured credit agreement with Credit Suisse AG, Cayman Islands Branch, as administrative agent, and the other lenders party thereto (the “Credit Agreement”). Of the other lenders, Oaktree funded approximately $40,476 of the $340,000 six-year term loan facility. In addition, as of July 3, 2013, Oaktree funded approximately $9,524 of the $80,000 delayed draw.
	On October 11, 2013, the Company obtained commitments from its current lenders with respect to a $70,000 incremental term loan under its Credit Agreement. On December 2, 2013, the Company borrowed $70,000 of the incremental term loans, and with such proceeds plus borrowings under its revolving line of credit and cash on hand, completed the redemption of all its outstanding Notes on December 4, 2013. Oaktree funded $10,000 of the $70,000 incremental term loan.

Investments_in_Unconsolidated_

Investments in Unconsolidated Investees	3 Months Ended
	Mar. 31, 2015
Investments in Unconsolidated Investees [Abstract]
Investments in Unconsolidated Investees	Investments in Unconsolidated Investees
	The Company has direct ownership in three unconsolidated investees at March 31, 2015. The Company owns between 15% and 50% of these investees, and provides management services under agreements with these investees, expiring at various dates through 2025. All of these investees are accounted for under the equity method since the Company does not exercise control over the operations of these investees.
	During 2014, in accordance with ASC 323, “Investments—Equity Method and Joint Ventures,” the Company wrote off its remaining investment in one of its unconsolidated investees that was originally acquired in 2011. The impairment charge totaled $236 and is related to the closure of one cancer center in the second quarter of 2014 due to the expiration of one of its non-compete agreements with the affiliated oncology physician. Impairment charges related to this event were taken in 2013 for a physicians' referral network, trademarks, and professional services agreement, which were all written down to zero value.
	Set forth below are certain financial data for Alliance-HNI, LLC and Subsidiaries, one of the Company’s unconsolidated investees as of:
		31-Dec-14		31-Mar-15
	Balance Sheet Data:
	Current assets	$	4,721	$	4,246
	Noncurrent assets	9,257		8,063
	Current liabilities	2,773		2,855
	Noncurrent liabilities	3,272		2,929
		Quarter Ended
		March 31,
		2014		2015
	Operating Results:
	Revenues	$	4,106	$	4,164
	Expenses	2,555		2,404
	Net income	1,551		1,760
	Earnings from unconsolidated investee	776		880
	Set forth below are certain financial data for the aggregate of the Company’s unconsolidated investees, including Alliance-HNI, LLC and Subsidiaries as of:
		31-Dec-14		31-Mar-15
	Balance Sheet Data:
	Current assets	$	8,687	$	7,494
	Noncurrent assets	10,108		8,763
	Current liabilities	3,760		3,822
	Noncurrent liabilities	3,395		2,965
		Quarter Ended
		March 31,
		2014		2015
	Combined Operating Results:
	Revenues	$	6,431	$	6,637
	Expenses	3,535		3,336
	Net income	2,896		3,301
	Earnings from unconsolidated investees	998		1,163

Stockholders_Deficit

Stockholders' Deficit	3 Months Ended
	Mar. 31, 2015
Stockholders' Equity Note [Abstract]
Stockholders' Deficit	Stockholders’ Deficit
	The following table summarizes consolidated stockholders’ deficit, including noncontrolling interest.
										Additional			Accumulated						Stockholders’ Equity (Deficit)					Total
																			Attributable to
		Common Stock			Treasury Stock					Paid-In			Comprehensive			Accumulated			Alliance HealthCare			Noncontrolling		Stockholders’
		Shares	Amount		Shares		Amount			Capital			Income (Loss)			Deficit			Services, Inc.			Interest		Deficit
	Balance at January 1, 2015	10,713,658	$	107	(157,973	)	$	(3,138	)	$	27,653		$	(351	)	$	(194,091	)	$	(169,820	)	$	58,340	$	(111,480	)
	Exercise of stock options	1,000	—		—		—			6			—			—			6			—		6
	Purchase of treasury stock	—	—		—		—			—			—			—			—			—		—
	Share-based payment	—	—		—		—			389			—			—			389			—		389
	Share-based payment income tax benefit	—	—		—		—			(82		)	—			—			(82		)	—		(82		)
	Unrealized loss on hedging transaction, net of tax	—	—		—		—			—			(128		)	—			(128		)	—		(128		)
	Net investments in subsidiaries	—	—		—		—			—			—			—			—			16,285		16,285
	Net income	—	—		—		—			—			—			1,751			1,751			4,347		6,098
	Balance at March 31, 2015	10,714,658	$	107	(157,973	)	$	(3,138	)	$	27,966		$	(479	)	$	(192,340	)	$	(167,884	)	$	78,972	$	(88,912	)

Segment_Information

Segment Information	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Segment Information	Segment Information
	Operating segments are defined as components of an enterprise about which separate financial information is available that is evaluated regularly by the chief operating decision maker (“CODM”) in deciding how to allocate resources and in assessing performance. In accordance with ASC 280, “Segment Reporting,” and based on the nature of the financial information that is received by the CODM, the Company operates in three operating segments, of which two are reportable segments, Imaging and Radiation Oncology, based on similar economic and other characteristics.
	The Imaging segment is comprised of diagnostic imaging services including MRI, PET/CT and other imaging services. The Radiation Oncology segment is comprised of radiation oncology services. All intercompany revenues, expenses, payables and receivables are eliminated in consolidation and are not reviewed when evaluating segment performance. Each segment’s performance is evaluated based on Revenue, Segment Income and Net Income. The accounting policies of the segments are the same as those described in the summary of significant accounting policies in Note 1 of the Notes to the Consolidated Financial Statements on Form 10-K for the year ended December 31, 2014. Additionally, the Company does not consider its wholesale revenue and retail revenue sources to constitute separate operating segments as discrete financial information does not exist and is not provided to the CODM.
	The following table summarizes the Company’s revenue by segment:
		Quarter Ended
		March 31,
		2014			2015
	Revenue
	Radiology	$	84,638		$	81,387
	Radiation Oncology	20,727			24,186
	Other	—			3,856
	Total	$	105,365		$	109,429
	The following are components of revenue:
		Quarter Ended
		March 31,
		2014			2015
	Revenue
	MRI revenue	$	44,185		$	42,887
	PET/CT revenue	33,369			31,550
	Radiation Oncology revenue	20,727			24,186
	Other radiology revenue	7,084			6,950
	Other revenue	—			3,856
	Total	$	105,365		$	109,429
	Segment income represents net income before income taxes; interest expense and other, net; amortization expense; depreciation expense; share-based payment; severance and related costs; noncontrolling interest in subsidiaries; restructuring charges; transaction costs; impairment charges, loss on extinguishment of debt, other non recurring charges, and non-cash charges. Segment income is the most frequently used measure of each segment’s performance by the CODM and is commonly used in setting performance goals. The following table summarizes the Company’s segment income (loss):
		Quarter Ended
		March 31,
		2014			2015
	Segment income
	Radiology	$	31,010		$	26,374
	Radiation Oncology	9,322			11,763
	Corporate / Other	(7,380		)	(8,021		)
	Total	$	32,952		$	30,116
	The reconciliation of Net income to total segment income is shown below:
		Quarter Ended
		March 31,
		2014			2015
	Net (loss) income attributable to Alliance HealthCare Services, Inc.	$	1,931		$	1,751
	Income tax (benefit) expense	1,507			1,572
	Interest expense and other, net	6,238			6,018
	Amortization expense	1,952			2,035
	Depreciation expense	15,795			11,633
	Share-based payment (included in selling, general and administrative expenses)	334			389
	Severance and related costs	—			259
	Noncontrolling interest in subsidiaries	3,049			4,347
	Restructuring charges (Note 2)	1,025			255
	Transaction costs	2			419
	Impairment charges	—			76
	Legal settlements	799			1,360
	Other non-cash charges (included in other income and expense, net)	320			2
	Total segment income	$	32,952		$	30,116
	Net income for the Radiology and Radiation Oncology segments does not include charges for interest expense, net of interest income, income taxes or certain selling, general and administrative expenses. These costs are charged against the Corporate / Other segment. The following table summarizes the Company’s net income (loss) by segment:
		Quarter Ended
		March 31,
		2014			2015
	Net income
	Radiology	$	17,194		$	16,997
	Radiation Oncology	3,426			5,024
	Corporate / Other	(18,689		)	(20,270		)
	Total	$	1,931		$	1,751
	The following table summarizes the Company’s identifiable assets by segment:
		As of December 31, 2014			As of March 31, 2015
	Identifiable assets
	Radiology	$	229,141		$	236,841
	Radiation Oncology	182,880			182,813
Corporate / Other	88,864			131,986
Total	$	500,885		$	551,640
The following table summarizes the Company’s goodwill by segment:
	Imaging			Radiation			Corporate		Total
				Oncology			/ Other
Balance at January 1, 2014	$	42,166		$	14,809		$	—	$	56,975
Goodwill acquired during the period	—			6,889			—		6,889
Impairment charges	—			—			—		—
Adjustments to goodwill during the period	—			—			—		—
Balance at December 31, 2014	$	42,166		$	21,698		$	—	$	63,864
Goodwill acquired during the period	—			—			22,610		22,610
Impairment charges	—			—			—		—
Adjustments to goodwill during the period	—			—			—		—
Balance at March 31, 2015	$	42,166		$	21,698		$	22,610	$	86,474
Gross goodwill	$	196,508		$	41,600		$	22,610	$	260,718
Accumulated impairment charges	(154,342		)	(19,902		)	—		(174,244		)
Balance at March 31, 2015	$	42,166		$	21,698		$	22,610	$	86,474
Cash used for capital expenditures for the Radiology, Radiation Oncology and Corporate segments were $6,830, $735, and $0, respectively, for the quarter ended March 31, 2015. Capital expenditures in the Radiology, Radiation Oncology and Corporate segments were $2,067, $0 and $3,668, respectively, for the quarter ended March 31, 2014.

Basis_of_Presentation_Principl1

Basis of Presentation, Principles of Consolidation, and Use of Estimates (Policies)	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared by Alliance HealthCare Services, Inc. (the “Company”) in accordance with accounting principles generally accepted in the United States of America and with the instructions to Form 10-Q and Article 10 of Regulation S-X of the Securities and Exchange Commission. Accordingly, they do not include all of the information and footnotes required by generally accepted accounting principles (“GAAP”) for complete financial statements. In the opinion of management, all adjustments (including normal recurring accruals) considered necessary for a fair presentation have been included. Operating results for the three months ended March 31, 2015 are not necessarily indicative of the results that may be expected for the year ending December 31, 2015. The accompanying unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes to the consolidated financial statements for the year ended December 31, 2014.
Principles of Consolidation	Principles of Consolidation The accompanying unaudited condensed consolidated financial statements of the Company include the assets, liabilities, revenues and expenses of all majority-owned subsidiaries over which the Company exercises control. Intercompany transactions have been eliminated. The Company records noncontrolling interest related to its consolidated subsidiaries which are not wholly owned. Investments in non-consolidated investees are accounted for under the equity method.
Use of Estimates	Use of Estimates The preparation of condensed consolidated financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. Actual results could differ from those estimates.
Share-based Payment	The Company has adopted ASC 718, “Compensation—Stock Compensation,” and has elected to follow the alternative transition method as described in ASC 718 for computing its beginning additional paid-in capital pool. In addition, the Company treats the tax deductions from stock options as being realized when they reduce taxes payable in accordance with the principles and timing under the relevant tax law.
Derivatives	The Company accounts for derivative instruments and hedging activities in accordance with the provisions of ASC 815, “Derivatives and Hedging.” Management generally designates derivatives in a hedge relationship with the identified exposure on the date the Company enters into a derivative contract, as disclosed below. The Company has only executed derivative instruments that are economic hedges of exposures that can qualify in hedge relationships under ASC 815. The Company formally documents all relationships between hedging instruments and hedged items, as well as the risk-management objective and strategy for undertaking various hedge transactions. In this documentation, the Company specifically identifies the firm commitment or forecasted transaction that has been designated as a hedged item and states how the hedging instrument is expected to hedge the risks related to the hedged item. The Company formally assesses effectiveness of its hedging relationships, both at the hedge inception and on an ongoing basis, then measures and records ineffectiveness. The Company would discontinue hedge accounting prospectively (i) if it is determined that the derivative is no longer effective in offsetting change in the cash flows of a hedged item, (ii) when the derivative expires or is sold, terminated or exercised, (iii) because it is probable that the forecasted transaction will not occur, or (iv) if management determines that designation of the derivative as a hedge instrument is no longer appropriate. The Company’s derivatives are recorded on the balance sheet at their fair value. For additional information please see Note 5 of the Notes to the Condensed Consolidated Financial Statements. For derivatives accounted for as cash flow hedges, any effective unrealized gains or losses on fair value are included in comprehensive income (loss), net of tax, and any ineffective gains or losses are recognized in income immediately. Amounts recorded in comprehensive income are reclassified to earnings when the hedged item impacts earnings.

Transactions_Transactions_Tabl

Transactions Transactions (Tables)	3 Months Ended
	Mar. 31, 2015
Business Combinations [Abstract]
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed	The following table summarizes recognized amounts of identifiable assets acquired and liabilities assumed at the acquisition date:
	Cash received	$	691
	Accounts receivable, net	4,440
	Equipment, net	3,346
	Other assets	416
	Goodwill	22,610
	Identifiable intangible assets	24,600
	Debt	(2,781		)
	Other liabilities	(3,531		)
	Noncontrolling interest	(20,598		)
	Cash consideration paid	$	29,193

ShareBased_Payment_Tables

Share-Based Payment (Tables)	3 Months Ended
	Mar. 31, 2015
Share-based Compensation [Abstract]
Weighted average assumptions for stock option awards	The following weighted average assumptions were used in the estimated grant date fair value calculations for stock option awards:
		Three months ended March 31,
		2014		2015
	Risk free interest rate	1.83	%	1.65	%
	Expected dividend yield	—	%	—	%
	Expected stock price volatility	66.3	%	65.2	%
	Average expected life (in years)	6		6
Summary of stock option activity	The following table summarizes the Company’s stock option activity:
		Number of		Weighted-		Weighted-	Aggregate
		Shares		Average		Average	Intrinsic
				Exercise Price		Remaining	Value
						Contractual
						Term
	Outstanding at January 1, 2015	633,898		$	21.39
	Granted	83,514		23.91
	Exercised	(1,000	)	6.2
	Canceled	(23,500	)	61.75
	Outstanding at March 31, 2015	692,912		$	20.36	6.28	$	4,510
	Vested and expected to vest in the future at March 31, 2015	666,254		$	20.21	6.2	$	4,487
	Exercisable at March 31, 2015	473,363		$	18.39	5.34	$	4,180
Summary of unvested stock option activity	The following table summarizes the Company’s unvested stock option activity:
		Shares		Weighted-Average
				Grant-Date
				Fair Value
	Unvested at January 1, 2015	197,899		$	12.13
	Granted	83,514		14.25
	Vested	(61,864	)	6.02
	Canceled	—		—
	Unvested at March 31, 2015	219,549		$	14.69
Summary of unvested restricted stock activity	The following table summarizes the Company’s restricted stock activity:
		Shares		Weighted-Average
				Grant-Date
				Fair Value
	Unvested at January 1, 2015	32,959		$	20.99
	Granted to employees	—		—
	Granted to non-employee directors	—		—
	Vested	—		—
	Canceled	—		—
	Unvested at March 31, 2015	32,959		$	20.99

Fair_Value_of_Financial_Instru1

Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Estimated fair values of financial instruments	The estimated fair values of the Company’s financial instruments are as follows:
		December 31, 2014				31-Mar-15
		Carrying		Fair		Carrying		Fair
		Value		Value		Value		Value
	Cash and cash equivalents	$	33,033	$	33,033	$	31,489	$	31,489
	Fixed-rate debt	13,015		13,878		23,814		24,070
	Variable-rate debt	494,274		494,354		510,512		509,577
	Contingent consideration related to acquisition	—		—		1,800		1,800
	Derivative instruments - asset position	228		228		48		48
	Derivative instruments - liability position	46		46		56		56
Financial instruments reported at fair value on a recurring basis	The following table summarizes the valuation of the Company’s financial instruments that are reported at fair value on a recurring basis by the above ASC 820 pricing levels as of December 31, 2014:
		Total		Quoted market		Significant other		Significant
				prices in active		observable  inputs		unobservable
				markets (Level 1)		(Level 2)		inputs (Level 3)
	Cash and cash equivalents	$	33,033	$	33,033	$	—	$	—
	Interest rate contracts - asset position	228				228
	Interest rate contracts - liability position	46		—		46		—
	The following table summarizes the valuation of the Company’s financial instruments that are reported at fair value on a recurring basis by the above ASC 820 pricing levels as of March 31, 2015:
		Total		Quoted market		Significant other		Significant
				prices in active		observable  inputs		unobservable
				markets (Level 1)		(Level 2)		inputs (Level 3)
	Cash and cash equivalents	$	31,489	$	31,489	$	—	$	—
	Interest rate contracts - asset position	48		—		48		—
	Interest rate contracts - liability position	56		—		56		—

Goodwill_and_Intangible_Assets1

Goodwill and Intangible Assets (Tables)	3 Months Ended
	Mar. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Changes in the carrying amount of goodwill	Changes in the carrying amount of goodwill are as follows:
	Balance at January 1, 2014	$	56,975
	Goodwill acquired during the period	6,889
	Impairment charges	—
	Adjustments to goodwill during the period	—
	Balance at December 31, 2014	63,864
	Goodwill acquired during the period	22,610
	Impairment charges	—
	Adjustments to goodwill during the period	—
	Balance at March 31, 2015	$	86,474
	Gross goodwill	$	260,718
	Accumulated impairment charges	(174,244		)
	Balance at March 31, 2015	$	86,474
Summary of intangible assets	Intangible assets consisted of the following:
		31-Dec-14								31-Mar-15
		Gross Carrying			Accumulated			Intangible		Gross Carrying		Accumulated			Intangible
		Amount			Amortization			Assets, net		Amount		Amortization			Assets, net
	Amortizing intangible assets:
	Customer contracts	$	162,089		$	(93,617	)	$	68,472	$	175,589	$	(95,440	)	$	80,149
	Other	26,241			(21,758		)	4,483		37,341		(21,970		)	15,371
	Total amortizing intangible assets	$	188,330		$	(115,375	)	$	72,955	$	212,930	$	(117,410	)	$	95,520
	Intangible assets not subject to amortization							42,975							42,975
	Total other intangible assets							$	115,930						$	138,495
Estimated annual amortization expense	Estimated annual amortization expense for each of the fiscal years ending December 31, is presented below:
	2015	$	8,599
	2016	7,904
	2017	7,466
	2018	7,105
	2019	6,621
	Thereafter	59,861

Other_Accrued_Liabilities_Tabl

Other Accrued Liabilities (Tables)	3 Months Ended
	Mar. 31, 2015
Other Accrued Liabilities [Abstract]
Components of other accrued liabilities	Other accrued liabilities consisted of the following:
		31-Dec-14		31-Mar-15
	Accrued systems rental and maintenance costs	$	1,586	$	2,105
	Accrued site rental fees	992		919
	Accrued property and sales taxes payable	9,276		9,591
	Accrued self-insurance expense	2,276		2,492
	Deferred gain on sale of equipment	312		312
	Other accrued expenses	12,100		12,444
	Total	$	26,542	$	27,863

LongTerm_Debt_and_Senior_Subor1

Long-Term Debt and Senior Subordinated Credit Facility (Tables)	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Components of long-term debt	Long-term debt consisted of the following:
		December 31,			31-Mar-15
		2014
	Term loan facility	$	482,825		$	476,699
	Discount on term loan facility	(2,156		)	(2,042		)
	Revolving credit facility	2,000			25,000
	Equipment debt	24,620			34,669
	Long-term debt, including current portion	507,289			534,326
	Less current portion	15,512			19,438
	Long-term debt	$	491,777		$	514,888

Derivatives_Tables

Derivatives (Tables)

3 Months Ended

Mar. 31, 2015

Summary of Derivative Instruments [Abstract]

Effect of Derivative Instruments on the Statement of Operations

The Effect of Designated Derivative Instruments on the Statement of Operations

For the Three Months Ended March 31, 2014

Derivatives in Cash

Amount of Gain (Loss)

Location of Gain

Amount of Gain (Loss)

Location of Gain

Amount of Gain (Loss)

Flow Hedging

Recognized in OCI on

(Loss)

Reclassified from

(Loss) Recognized in

Recognized in Income

Relationships

Derivatives (Effective

Reclassified from

Accumulated OCI into

Income on Derivatives

on Derivatives

Portion)

Accumulated OCI into

Income (Effective

(Ineffective Portion)

(Ineffective Portion)

Income (Effective

Portion)

Portion)

Interest rate contracts

$

(103

)

Interest expense and other, net

$

(134

)

Interest expense and other, net

$

(2

)

The Effect of Designated Derivative Instruments on the Statement of Operations

For the Three Months Ended March 31, 2015

Derivatives in Cash

Amount of Gain (Loss)

Location of Gain

Amount of Gain (Loss)

Location of Gain

Amount of Gain (Loss)

Flow Hedging

Recognized in OCI on

(Loss)

Reclassified from

(Loss) Recognized in

Recognized in Income

Relationships

Derivatives (Effective

Reclassified from

Accumulated OCI into

Income on Derivatives

on Derivatives

Portion)

Accumulated OCI into

Income (Effective

(Ineffective Portion)

(Ineffective Portion)

Income (Effective

Portion)

Portion)

Interest rate contracts

$

(189

)

Interest expense and other, net

$

11

Interest expense and other, net

$

1

Earnings_Per_Common_Share_Tabl

Earnings Per Common Share (Tables)	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Computation of basic and diluted loss per share	The following table sets forth the computation of basic and diluted earnings per share:
		Quarter Ended
		March 31,
		2014		2015
	Numerator:
	Net income attributable to Alliance HealthCare Services, Inc.	$	1,931	$	1,751
	Denominator:
	Weighted-average shares-basic	10,666		10,714
	Effect of dilutive securities:
	Employee stock options	224		128
	Weighted-average shares-diluted	10,890		10,842
	Income per common share attributable to Alliance HealthCare Services, Inc.:
	Basic	$	0.18	$	0.16
	Diluted	$	0.18	$	0.16
	Stock options excluded from the computation of diluted per share amounts:
	Weighted-average shares for which the exercise price exceeds average market price of common stock	135		310
	Average exercise price per share that exceeds average market price of common stock	$	44.29	$	32.2

Investments_in_Unconsolidated_1

Investments in Unconsolidated Investees (Tables)	3 Months Ended
	Mar. 31, 2015
Alliance-HNI, LLC and Subsidiaries
Schedule Of Equity Method Investments [Line Items]
Schedule of financial data of unconsolidated investees, Balance Sheet Data	Set forth below are certain financial data for Alliance-HNI, LLC and Subsidiaries, one of the Company’s unconsolidated investees as of:
		31-Dec-14		31-Mar-15
	Balance Sheet Data:
	Current assets	$	4,721	$	4,246
	Noncurrent assets	9,257		8,063
	Current liabilities	2,773		2,855
	Noncurrent liabilities	3,272		2,929
Schedule of financial data of unconsolidated investees, Combined Operating Results
		Quarter Ended
		March 31,
		2014		2015
	Operating Results:
	Revenues	$	4,106	$	4,164
	Expenses	2,555		2,404
	Net income	1,551		1,760
	Earnings from unconsolidated investee	776		880
Unconsolidated Investees, Including Alliance-HNI, LLC and Subsidiaries and Austin Cyberknife
Schedule Of Equity Method Investments [Line Items]
Schedule of financial data of unconsolidated investees, Balance Sheet Data	Set forth below are certain financial data for the aggregate of the Company’s unconsolidated investees, including Alliance-HNI, LLC and Subsidiaries as of:
		31-Dec-14		31-Mar-15
	Balance Sheet Data:
	Current assets	$	8,687	$	7,494
	Noncurrent assets	10,108		8,763
	Current liabilities	3,760		3,822
	Noncurrent liabilities	3,395		2,965
Schedule of financial data of unconsolidated investees, Combined Operating Results
		Quarter Ended
		March 31,
		2014		2015
	Combined Operating Results:
	Revenues	$	6,431	$	6,637
	Expenses	3,535		3,336
	Net income	2,896		3,301
	Earnings from unconsolidated investees	998		1,163

Stockholders_Deficit_Tables

Stockholders' Deficit (Tables)	3 Months Ended
	Mar. 31, 2015
Stockholders' Equity Note [Abstract]
Summary of stockholders' deficit, including noncontrolling interest	The following table summarizes consolidated stockholders’ deficit, including noncontrolling interest.
										Additional			Accumulated						Stockholders’ Equity (Deficit)					Total
																			Attributable to
		Common Stock			Treasury Stock					Paid-In			Comprehensive			Accumulated			Alliance HealthCare			Noncontrolling		Stockholders’
		Shares	Amount		Shares		Amount			Capital			Income (Loss)			Deficit			Services, Inc.			Interest		Deficit
	Balance at January 1, 2015	10,713,658	$	107	(157,973	)	$	(3,138	)	$	27,653		$	(351	)	$	(194,091	)	$	(169,820	)	$	58,340	$	(111,480	)
	Exercise of stock options	1,000	—		—		—			6			—			—			6			—		6
	Purchase of treasury stock	—	—		—		—			—			—			—			—			—		—
	Share-based payment	—	—		—		—			389			—			—			389			—		389
	Share-based payment income tax benefit	—	—		—		—			(82		)	—			—			(82		)	—		(82		)
	Unrealized loss on hedging transaction, net of tax	—	—		—		—			—			(128		)	—			(128		)	—		(128		)
	Net investments in subsidiaries	—	—		—		—			—			—			—			—			16,285		16,285
	Net income	—	—		—		—			—			—			1,751			1,751			4,347		6,098
	Balance at March 31, 2015	10,714,658	$	107	(157,973	)	$	(3,138	)	$	27,966		$	(479	)	$	(192,340	)	$	(167,884	)	$	78,972	$	(88,912	)

Segment_Information_Tables

Segment Information (Tables)	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Summary of revenue by segment	The following table summarizes the Company’s revenue by segment:
		Quarter Ended
		March 31,
		2014			2015
	Revenue
	Radiology	$	84,638		$	81,387
	Radiation Oncology	20,727			24,186
	Other	—			3,856
	Total	$	105,365		$	109,429
	The following are components of revenue:
		Quarter Ended
		March 31,
		2014			2015
	Revenue
	MRI revenue	$	44,185		$	42,887
	PET/CT revenue	33,369			31,550
	Radiation Oncology revenue	20,727			24,186
	Other radiology revenue	7,084			6,950
	Other revenue	—			3,856
	Total	$	105,365		$	109,429
Summary of segment income	The following table summarizes the Company’s segment income (loss):
		Quarter Ended
		March 31,
		2014			2015
	Segment income
	Radiology	$	31,010		$	26,374
	Radiation Oncology	9,322			11,763
	Corporate / Other	(7,380		)	(8,021		)
	Total	$	32,952		$	30,116
Reconciliation of Net loss to total segment income	The reconciliation of Net income to total segment income is shown below:
		Quarter Ended
		March 31,
		2014			2015
	Net (loss) income attributable to Alliance HealthCare Services, Inc.	$	1,931		$	1,751
	Income tax (benefit) expense	1,507			1,572
	Interest expense and other, net	6,238			6,018
	Amortization expense	1,952			2,035
	Depreciation expense	15,795			11,633
	Share-based payment (included in selling, general and administrative expenses)	334			389
	Severance and related costs	—			259
	Noncontrolling interest in subsidiaries	3,049			4,347
	Restructuring charges (Note 2)	1,025			255
	Transaction costs	2			419
	Impairment charges	—			76
	Legal settlements	799			1,360
	Other non-cash charges (included in other income and expense, net)	320			2
	Total segment income	$	32,952		$	30,116
Summary of net income (loss) by segment	The following table summarizes the Company’s net income (loss) by segment:
		Quarter Ended
		March 31,
		2014			2015
	Net income
	Radiology	$	17,194		$	16,997
	Radiation Oncology	3,426			5,024
	Corporate / Other	(18,689		)	(20,270		)
	Total	$	1,931		$	1,751
Summary of Company's identifiable assets by segment	The following table summarizes the Company’s identifiable assets by segment:
		As of December 31, 2014			As of March 31, 2015
	Identifiable assets
	Radiology	$	229,141		$	236,841
	Radiation Oncology	182,880			182,813
	Corporate / Other	88,864			131,986
	Total	$	500,885		$	551,640
Summary of company's goodwill by segment	The following table summarizes the Company’s goodwill by segment:
		Imaging			Radiation			Corporate		Total
					Oncology			/ Other
	Balance at January 1, 2014	$	42,166		$	14,809		$	—	$	56,975
	Goodwill acquired during the period	—			6,889			—		6,889
	Impairment charges	—			—			—		—
	Adjustments to goodwill during the period	—			—			—		—
	Balance at December 31, 2014	$	42,166		$	21,698		$	—	$	63,864
	Goodwill acquired during the period	—			—			22,610		22,610
	Impairment charges	—			—			—		—
	Adjustments to goodwill during the period	—			—			—		—
	Balance at March 31, 2015	$	42,166		$	21,698		$	22,610	$	86,474
	Gross goodwill	$	196,508		$	41,600		$	22,610	$	260,718
	Accumulated impairment charges	(154,342		)	(19,902		)	—		(174,244		)
	Balance at March 31, 2015	$	42,166		$	21,698		$	22,610	$	86,474

Transactions_Additional_Inform

Transactions - Additional Information (Details) (USD $)	3 Months Ended		0 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Feb. 17, 2015	Dec. 31, 2014	Dec. 31, 2013
			center
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$255	$1,025
Goodwill	86,474			63,864	56,975
Revenues	109,429	105,365
Net income attributable to Alliance HealthCare Services, Inc.	1,751	1,931
The Pain Center of Arizona, PC
Restructuring Cost and Reserve [Line Items]
Percentage of voting interests acquired			59.00%
Number of locations operated by entity			12
Percentage of voting interests acquired before dilution			60.00%
Payments to acquire businesses, gross			23,630
Cash received			691
Accounts receivable extinguishment, related parties			3,071
Goodwill			22,610
Identifiable intangible assets			24,600
Useful life			20 years
Weighted average useful life			15 years
Noncontrolling interest, fair value			20,598
Revenues	3,855
Net income attributable to Alliance HealthCare Services, Inc.	271
Contingent consideration performance period (in months)	12 months
Contingent consideration	1,800
The Pain Center of Arizona, PC | Physician referral network intangible assets
Restructuring Cost and Reserve [Line Items]
Identifiable intangible assets			13,500
The Pain Center of Arizona, PC | Trademarks
Restructuring Cost and Reserve [Line Items]
Identifiable intangible assets			11,100
Medical Practice Innovations, Inc.
Restructuring Cost and Reserve [Line Items]
Percentage of voting interests acquired			50.00%
Selling, general and administrative expenses
Restructuring Cost and Reserve [Line Items]
Restructuring charges	55	704
Severance and related costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	259	133
Cost of revenues, excluding depreciation and amortization
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$200	$188

Transactions_Recognized_Identi

Transactions - Recognized Identifiable Assets and Liabilities (Details) (USD $)	0 Months Ended
In Thousands, unless otherwise specified	Feb. 17, 2015	Mar. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Business Acquisition [Line Items]
Goodwill		$86,474	$63,864	$56,975
The Pain Center of Arizona, PC
Business Acquisition [Line Items]
Cash received	691
Accounts receivable, net	4,440
Equipment, net	3,346
Other assets	416
Goodwill	22,610
Identifiable intangible assets	24,600
Debt	2,781
Other liabilities	3,531
Noncontrolling interest	-20,598
Cash consideration paid	$29,193

ShareBased_Payment_Weighted_Av

Share-Based Payment - Weighted Average Assumptions for Fair Value of Stock Options (Details)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Weighted average assumptions for stock option awards
Risk free interest rate	1.65%	1.83%
Expected dividend yield	0.00%	0.00%
Expected stock price volatility	65.20%	66.30%
Average expected life (in years)	6 years	6 years

ShareBased_Payment_Stock_Optio

Share-Based Payment - Stock Option Activity (Details) (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Summary of stock option activity
Begining balance (shares)	633,898
Granted (shares)	83,514
Exercised (shares)	-1,000	-7,667
Canceled (shares)	-23,500
Ending balance (shares)	692,912
Vested and expected to vest (shares)	666,254
Exercisable (shares)	473,363
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Roll Forward]
Beginning balance, weighted-average exercise price (dollars per share)	$21.39
Granted, weighted-average exercise price (dollars per share)	$23.91
Exercised, weighted-average exercise price (dollars per share)	$6.20
Canceled, weighted-average exercise price (dollars per share)	$61.75
Ending balance, weighted-average exercise price (dollars per share)	$20.36
Vested and expected to vest, weighted-average exercise price (dollars per share)	$20.21
Exercisable, weighted-average exercise price (dollars per share)	$18.39
Outstanding, weighted-average remaining contractual term (in years)	6 years 3 months 11 days
Vested and expected to vest, weighted-average remaining contractual term (in years)	6 years 2 months 11 days
Exercisable, weighted-average remaining contractual term (in years)	5 years 4 months 1 day
Outstanding, aggregate intrinsic value	$4,510
Vested and expected to vest, aggregate intrinsic value	4,487
Exercisable, aggregate intrinsic value	$4,180

ShareBased_Payment_Unvested_St

Share-Based Payment - Unvested Stock Activity (Details) (USD $)	3 Months Ended
	Mar. 31, 2015
Unvested stock option
Summary of unvested stock option activity
Beginning balance, unvested shares (shares)	197,899
Granted, unvested share (shares)	83,514
Vested, unvested share (shares)	-61,864
Canceled, unvested share (shares)	0
Ending balance, unvested shares (shares)	219,549
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Beginning balance, unvested shares, weighted-average grant-date fair value (dollars per share)	$12.13
Granted, unvested shares, weighted-average grant-date fair value (dollars per share)	$14.25
Vested, unvested shares, weighted-average grant-date fair value (dollars per share)	$6.02
Canceled, unvested shares, weighted-average grant-date fair value (dollars per share)	$0
Ending balance, unvested shares, weighted-average grant-date fair value (dollars per share)	$14.69
Restricted stock
Summary of unvested stock option activity
Beginning balance, unvested shares (shares)	32,959
Vested, unvested share (shares)	0
Canceled, unvested share (shares)	0
Ending balance, unvested shares (shares)	32,959
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Beginning balance, unvested shares, weighted-average grant-date fair value (dollars per share)	$20.99
Vested, unvested shares, weighted-average grant-date fair value (dollars per share)	$0
Canceled, unvested shares, weighted-average grant-date fair value (dollars per share)	$0
Ending balance, unvested shares, weighted-average grant-date fair value (dollars per share)	$20.99
Employees | Restricted stock
Summary of unvested stock option activity
Granted, unvested share (shares)	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Granted, unvested shares, weighted-average grant-date fair value (dollars per share)	$0
Non-employee directors | Restricted stock
Summary of unvested stock option activity
Granted, unvested share (shares)	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Granted, unvested shares, weighted-average grant-date fair value (dollars per share)	$0

ShareBased_Payment_Textual_Det

Share-Based Payment - Textual (Details) (USD $)	3 Months Ended		12 Months Ended			3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Sep. 30, 2014	Nov. 30, 1999
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares available for options and awards (shares)	472,391						2,205,000
Options term (years)	10 years
Options accelerated due to employment agreements vesting (shares)	0		0
Weighted average grant date fair value (dollars per share)	$14.25	$17.56
Stock options exercised (shares)	1,000	7,667
Total unrecognized fair value related to unvested stock options	$2,353,000
Recognized weighted-average period (years)	2 years 3 months 20 days
Total fair value of shares vested	372,000	360,000
Non-Employee Director Serving as Member of Audit Committee [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Noninterest expense directors fees		15,000
Non-Employee Director Serving as Chairman of Audit Committee [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Noninterest expense directors fees		30,000
Non-Employee Director Serving As Member of Nominating Committee, Compensation Committee, and Strategy and Finance Committee [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Noninterest expense directors fees		5,000
Non-Employee Director Serving as Chairman of Strategy and Finance Committee [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Noninterest expense directors fees		25,000
Directors' Deferred Compensation Plan [Member] | Non-employee directors
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Noninterest expense directors fees	40,000		40,000
Directors' Deferred Compensation Plan [Member] | Unaffiliated directors
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Noninterest expense directors fees	140,000
Fair value of shares issued	140,000
Time option | 1999 Equity Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Subsequent stock options, vesting after one year (percent)	5.00%
Subsequent stock options, vesting after two year (percent)	20.00%
Subsequent stock options, vesting after three year (percent)	25.00%
Subsequent stock options, vesting after four year (percent)	25.00%
Subsequent stock options, vesting after five year (percent)	25.00%
Restricted Stock Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period (years)				1 year	3 years
Options, typically vesting each year from the date of grant (percent)					33.30%
Share-based payment	172,000	92,000
Restricted Stock Awards | Employees
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total unrecognized fair value related to unvested stock options	0
Non-option equity instruments, granted		0
Number of awards to non-employees (shares)	0
Restricted Stock Awards | Non-employee directors
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of awards to non-employees (shares)	0
Restricted Stock Awards | Unaffiliated directors
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period (years)				1 year
Total unrecognized fair value related to unvested stock options	517,000
Recognized weighted-average period (years)	9 months
Period in force proceeding grant date	15 days
Restricted Stock Awards | Board of Directors Chairman [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Fair value of shares issued	$138,000
Requisite service period	P1Y
Period after resignation in which entitlement is valid	24 months
Restricted Stock Awards | Cliff vest after one year
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period (years)					1 year
Restricted Stock Units (RSUs) [Member] | Executive Management [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of awards to non-employees (shares)						25,000
Minimum market price that must be achieved	$40
Duration of minimum market price	10 days
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period (years)	3 years
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period (years)	4 years

Fair_Value_of_Financial_Instru2

Fair Value of Financial Instruments - Estimated Fair Value of Financial Instruments (Details) (Fair Value, Measurements, Recurring, USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Estimated fair values of financial instruments
Cash and cash equivalents	$31,489	$33,033
Carrying Value
Estimated fair values of financial instruments
Cash and cash equivalents	31,489	33,033
Fixed-rate debt	23,814	13,015
Variable-rate debt	510,512	494,274
Contingent consideration	1,800	0
Derivative instruments - asset position	48	228
Derivative instruments - liability position	56	46
Fair Value
Estimated fair values of financial instruments
Cash and cash equivalents	31,489	33,033
Fixed-rate debt	24,070	13,878
Variable-rate debt	509,577	494,354
Contingent consideration	1,800	0
Derivative instruments - asset position	48	228
Derivative instruments - liability position	$56	$46

Fair_Value_of_Financial_Instru3

Fair Value of Financial Instruments - Summary of Valuation of Financial Instruments Reported at Fair Value on a Recurring Basis by Pricing Level (Details) (Recurring basis, USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Financial instruments reported at fair value on a recurring basis
Cash and cash equivalents	$31,489	$33,033
Interest rate contracts
Financial instruments reported at fair value on a recurring basis
Interest rate contracts - asset position	48	228
Interest rate contracts - liability position	56	46
Quoted market prices in active markets (Level 1)
Financial instruments reported at fair value on a recurring basis
Cash and cash equivalents	31,489	33,033
Quoted market prices in active markets (Level 1) | Interest rate contracts
Financial instruments reported at fair value on a recurring basis
Interest rate contracts - asset position	0
Interest rate contracts - liability position	0	0
Significant other observable inputs (Level 2)
Financial instruments reported at fair value on a recurring basis
Cash and cash equivalents	0	0
Significant other observable inputs (Level 2) | Interest rate contracts
Financial instruments reported at fair value on a recurring basis
Interest rate contracts - asset position	48	228
Interest rate contracts - liability position	56	46
Significant unobservable inputs (Level 3)
Financial instruments reported at fair value on a recurring basis
Cash and cash equivalents	0	0
Significant unobservable inputs (Level 3) | Interest rate contracts
Financial instruments reported at fair value on a recurring basis
Interest rate contracts - asset position	0
Interest rate contracts - liability position	$0	$0

Goodwill_and_Intangible_Assets2

Goodwill and Intangible Assets - Goodwill Rollforward (Details) (USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Changes in the Carrying Amount of Goodwill
Beginning balance	$63,864	$56,975
Goodwill acquired during the period	22,610	6,889
Impairment charges	0	0
Adjustments to goodwill during the period	0	0
Ending balance	86,474	63,864
Gross goodwill	260,718
Accumulated impairment charges	($174,244)

Goodwill_and_Intangible_Assets3

Goodwill and Intangible Assets - Components of Intangible Assets (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Amortizing intangible assets:
Gross Carrying Amount	$212,930	$188,330
Accumulated Amortization	-117,410	-115,375
Intangible Assets, net	95,520	72,955
Intangible assets not subject to amortization	42,975	42,975
Total other intangible assets	138,495	115,930
Customer contracts
Amortizing intangible assets:
Gross Carrying Amount	175,589	162,089
Accumulated Amortization	-95,440	-93,617
Intangible Assets, net	80,149	68,472
Other
Amortizing intangible assets:
Gross Carrying Amount	37,341	26,241
Accumulated Amortization	-21,970	-21,758
Intangible Assets, net	$15,371	$4,483

Goodwill_and_Intangible_Assets4

Goodwill and Intangible Assets - Estimated Annual Amortization Expense (Details) (USD $)	Mar. 31, 2015
In Thousands, unless otherwise specified
Estimated annual amortization expense
2015	$8,599
2016	7,904
2017	7,466
2018	7,105
2019	6,621
Thereafter	$59,861

Goodwill_and_Intangible_Assets5

Goodwill and Intangible Assets - Textual (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Goodwill and Intangible Assets (Textual) [Abstract]
Amortization expense	$2,035	$1,952
Customer contracts
Goodwill and Intangible Assets (Textual) [Abstract]
Weighted-average estimated useful life of amortization intangible assets (years)	15 years
Other intangible assets
Goodwill and Intangible Assets (Textual) [Abstract]
Weighted-average estimated useful life of amortization intangible assets (years)	6 years

Other_Accrued_Liabilities_Deta

Other Accrued Liabilities (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Components of other accrued liabilities
Accrued systems rental and maintenance costs	$2,105	$1,586
Accrued site rental fees	919	992
Accrued property and sales taxes payable	9,591	9,276
Accrued self-insurance expense	2,492	2,276
Deferred gain on sale of equipment	312	312
Other accrued expenses	12,444	12,100
Total	$27,863	$26,542

LongTerm_Debt_and_Senior_Subor2

Long-Term Debt and Senior Subordinated Credit Facility - Schedule of Long-term Debt (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Debt Instrument [Line Items]
Long-term debt, including current portion	$534,326	$507,289
Current portion of long-term debt	19,438	15,512
Long-term debt	514,888	491,777
Term Loan Facility
Debt Instrument [Line Items]
Long-term debt, gross	476,699	482,825
Discount on term loan facility	-2,042	-2,156
Revolving Credit Facility
Debt Instrument [Line Items]
Revolving credit facility	25,000	2,000
Equipment Debt [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$34,669	$24,620

LongTerm_Debt_and_Senior_Subor3

Long-Term Debt and Senior Subordinated Credit Facility - Additional Information (Details) (USD $)	3 Months Ended		0 Months Ended			1 Months Ended	0 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Jun. 03, 2013	Jul. 03, 2013	Jun. 03, 2013	Dec. 31, 2009	Oct. 11, 2013	Dec. 02, 2013	Dec. 31, 2004
Debt Instrument [Line Items]
Repayments of long-term debt	$6,126,000	$1,225,000
Maximum
Debt Instrument [Line Items]
Ownership percentage of subsidiaries	50.00%
Minimum
Debt Instrument [Line Items]
Ownership percentage of subsidiaries	15.00%
Term Loan Facility | Base Rate
Debt Instrument [Line Items]
Debt floor interest rate (percent)			4.25%		4.25%
Revolving Credit Facility | LIBOR
Debt Instrument [Line Items]
Debt floor interest rate (percent)			2.00%		2.00%
Revolving Credit Facility | Base Rate
Debt Instrument [Line Items]
Debt floor interest rate (percent)			5.25%		5.25%
Revolving Credit Facility | Maximum
Debt Instrument [Line Items]
Debt, leverage ratio			0.005		0.005
Revolving Credit Facility | Minimum
Debt Instrument [Line Items]
Debt, leverage ratio			0.00375		0.00375
Committed Incremental Term Loan
Debt Instrument [Line Items]
Percent of subsidiary owned to qualify for loan guarantee	50.00%
New Credit Agreement
Debt Instrument [Line Items]
Ownership percentage of subsidiaries			50.00%		50.00%
New Credit Agreement | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (percent)			1.00%
Debt description of variable rate basis			one-month LIBOR
New Credit Agreement | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate (percent)			0.50%
New Credit Agreement | Term Loan Facility
Debt Instrument [Line Items]
Term loan facility borrowing capacity			340,000,000	340,000,000	340,000,000
Debt term (years)			6 years
Repayments of long-term debt				80,000,000
Revolving credit facility	476,699,000
Actual ratio of consolidated total debt to Consolidated Adjusted EBITDA	3.75
New Credit Agreement | Term Loan Facility | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (percent)			3.25%
New Credit Agreement | Term Loan Facility | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate (percent)			2.25%
New Credit Agreement | Term Loan Facility | Maximum
Debt Instrument [Line Items]
Debt, leverage ratio	4.85		3.25		3.25
Covenant ratio of consolidated total debt to Consolidated Adjusted EBITDA, current year	4.95
New Credit Agreement | Term Loan Facility | Minimum
Debt Instrument [Line Items]
Covenant ratio of consolidated total debt to Consolidated Adjusted EBITDA, current year	4.3
New Credit Agreement | Revolving Credit Facility
Debt Instrument [Line Items]
Term loan facility borrowing capacity			50,000,000		50,000,000
Debt term (years)			5 years
Revolving credit facility	25,000,000
New Credit Agreement | Revolving Credit Facility | LIBOR
Debt Instrument [Line Items]
Debt floor interest rate (percent)			1.00%		1.00%
New Credit Agreement | Revolving Credit Facility | Maximum | LIBOR
Debt Instrument [Line Items]
Debt, leverage ratio			0.0325		0.0325
New Credit Agreement | Revolving Credit Facility | Maximum | Base Rate
Debt Instrument [Line Items]
Debt, leverage ratio			0.0225		0.0225
New Credit Agreement | Revolving Credit Facility | Minimum | LIBOR
Debt Instrument [Line Items]
Debt, leverage ratio			0.03		0.03
New Credit Agreement | Revolving Credit Facility | Minimum | Base Rate
Debt Instrument [Line Items]
Debt, leverage ratio			0.02		0.02
New Credit Agreement | Letter of Credit
Debt Instrument [Line Items]
Term loan facility borrowing capacity			20,000,000		20,000,000
New Credit Agreement | Uncommitted Incremental Loan Facility
Debt Instrument [Line Items]
Term loan facility borrowing capacity			100,000,000		100,000,000
New Credit Agreement | Delayed Draw
Debt Instrument [Line Items]
Term loan facility borrowing capacity			80,000,000		80,000,000
Debt, quarterly payments at debt capacity			1,050,000
Debt Instrument, Period Quarterly Amortization Payments Required					5 years 9 months
New Credit Agreement | Senior notes
Debt Instrument [Line Items]
Long-term debt, gross			190,000,000		190,000,000
Discount rate on debt (percent)						8.25%
New Credit Agreement | Committed Incremental Term Loan
Debt Instrument [Line Items]
Term loan facility borrowing capacity	70,000,000						70,000,000	70,000,000
Percentage of principal amount funded							99.00%
Revolving credit facility								70,000,000
New Credit Agreement | Committed Incremental Term Loan | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (percent)							3.25%
Debt floor interest rate (percent)							1.00%
New Credit Agreement | Committed Incremental Term Loan | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate (percent)							2.25%
New Credit Agreement | Committed Incremental Term Loan | Maximum
Debt Instrument [Line Items]
Debt instrument, periodic payment	1,225,000
New Credit Agreement | Committed Incremental Term Loan | Minimum
Debt Instrument [Line Items]
Debt instrument, periodic payment	$1,050,000
Senior Notes, 7.25 Percent [Member] | Senior notes
Debt Instrument [Line Items]
Debt Instrument, Interest Rate, Stated Percentage									7.25%

Derivatives_Textual_Details

Derivatives - Textual (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2010	Jun. 30, 2011	Dec. 31, 2012
				agreement
Interest Rate Cash Flow Hedges
Derivative [Line Items]
Variable bank rate debt	$257,902	$259,320
Variable rate debt as a percent of total debt (percent)	48.30%	50.40%
Expected reclassification from accumulated other comprehensive loss to interest expense and other, net	195
Number of agreements					2
Interest rate cap
Derivative [Line Items]
Derivative, notional amount	250,000
Paid for cap purchase amortized as interest expense			815
Interest rate agreement, basis spread on variable rate (percent)	2.50%
Interest rate cap | Interest Rate Cash Flow Hedges
Derivative [Line Items]
Number of agreements				3
Maturity				1-Feb-14
Derivative, notional amount				150,000
Interest rate cap | Interest Rate Cash Flow Hedges | LIBOR
Derivative [Line Items]
Derivative variable rate basis				LIBOR
USR Swap one | Interest Rate Cash Flow Hedges
Derivative [Line Items]
Maturity					1-Oct-15
Derivative, notional amount	610
Fixed rate of interest paid by the Company (percent)					5.71%
Recorded interest expense rate (percent)					8.71%
Underlying debt interest rate (percent)					3.00%
USR Swap one | Interest Rate Cash Flow Hedges | LIBOR
Derivative [Line Items]
Derivative variable rate basis					one-month LIBOR
USR Swap two | Interest Rate Cash Flow Hedges
Derivative [Line Items]
Maturity					1-Apr-14
Interest Rate Swap, Maturing December 2017
Derivative [Line Items]
Derivative, notional amount	2,976
Fixed rate of interest paid by the Company (percent)	3.75%
Recorded interest expense rate (percent)	3.75%
Interest rate agreement, basis spread on variable rate (percent)	2.50%
Interest Rate Swap, Maturing December 2017 | LIBOR
Derivative [Line Items]
Derivative variable rate basis						one-month LIBOR
Interest rate agreement, basis spread on variable rate (percent)	2.50%
Interest Rate Swap, Matures April 2018
Derivative [Line Items]
Derivative, notional amount	2,710
Fixed rate of interest paid by the Company (percent)	2.87%
Recorded interest expense rate (percent)	2.87%
Interest rate agreement, basis spread on variable rate (percent)	2.00%
Interest Rate Swap, Matures April 2018 | LIBOR
Derivative [Line Items]
Derivative variable rate basis	one-month LIBOR
Interest rate agreement, basis spread on variable rate (percent)	2.00%
Interest Rate Swap [Member]
Derivative [Line Items]
Derivative, notional amount	$1,605
Interest rate agreement, basis spread on variable rate (percent)	1.34%

Derivatives_Income_Statement_I

Derivatives - Income Statement Impact (Details) (Designated Derivative Instruments, Derivatives in Cash Flow Hedging Relationships, Interest rate contracts, USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Effect of Derivative Instruments on Statement of Operations
Amount of Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)	($189)	($103)
Interest expense and other, net
Effect of Derivative Instruments on Statement of Operations
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	11	-134
Amount of Gain (Loss) Recognized in Income on Derivatives (Ineffective Portion)	$1	($2)

Income_Taxes_Details

Income Taxes (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Income Tax Disclosure [Abstract]
Income tax (benefit) expense	$1,572	$1,507
Income tax benefit (percentage)	47.30%	43.80%
Unrecognized tax benefits related to various federal and state income tax matters	285
Tax-effected amount that would reduce the company's effective income tax rate if recognized	243
Accrued interest and penalties related to unrecognized tax benefits	$14

Earnings_Per_Common_Share_Deta

Earnings Per Common Share (Details) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Numerator [Abstract]
Net income attributable to Alliance HealthCare Services, Inc.	$1,751	$1,931
Denominator [Abstract]
Weighted-average shares-basic (shares)	10,714	10,666
Effect of dilutive securities:
Employee stock options (shares)	128	224
Weighted-average shares-diluted (shares)	10,842	10,890
Income per common share attributable to Alliance HealthCare Services, Inc.:
Basic (dollars per share)	$0.16	$0.18
Diluted (dollars per share)	$0.16	$0.18
Stock options excluded from the computation of diluted per share amounts:
Weighted-average shares for which exercise price exceeds average market price of common stock (shares)	310	135
Average exercise price per share that exceeds average market price of common stock (dollars per share)	$32.20	$44.29

Commitments_and_Contingencies_

Commitments and Contingencies (Details) (USD $)	0 Months Ended
	Mar. 27, 2013	Mar. 31, 2015
Commitments and Contingencies [Line Items]
Liability related to guarantees and indemnities		$0
Superior MRI Services, Inc.
Commitments and Contingencies [Line Items]
Damages sought (in excess of)	$1,000,000

RelatedParty_Transactions_Deta

Related-Party Transactions (Details) (USD $)	3 Months Ended		0 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Jun. 03, 2013	Apr. 16, 2007	Jul. 03, 2013	Dec. 02, 2013	Oct. 11, 2013
Related Party Transaction [Line Items]
Shares purchased by Oaktree and MTS (shares)				4,900,301
Percentage of outstanding stock owned by Oaktree and MTS (percent)	50.70%			49.70%
Revenues from management agreements with unconsolidated equity investees	$2,378,000	$2,321,000
Amounts of the revenues and expenses	1,947,000	1,904,000
New Credit Agreement | Term Loan Facility
Related Party Transaction [Line Items]
Debt amount funded	476,699,000
Term loan facility borrowing capacity			340,000,000		340,000,000
Debt term (years)			6 years
New Credit Agreement | Delayed Draw
Related Party Transaction [Line Items]
Term loan facility borrowing capacity			80,000,000
New Credit Agreement | Committed Incremental Term Loan
Related Party Transaction [Line Items]
Debt amount funded						70,000,000
Term loan facility borrowing capacity	70,000,000					70,000,000	70,000,000
New Credit Agreement | Oaktree [Member] | Term Loan Facility
Related Party Transaction [Line Items]
Debt amount funded			40,476,000
Term loan facility borrowing capacity			340,000,000
Debt term (years)			6 years
New Credit Agreement | Oaktree [Member] | Delayed Draw
Related Party Transaction [Line Items]
Debt amount funded					9,524,000
Term loan facility borrowing capacity					80,000,000
New Credit Agreement | Oaktree [Member] | Committed Incremental Term Loan
Related Party Transaction [Line Items]
Term loan facility borrowing capacity	$10,000,000

Investments_in_Unconsolidated_2

Investments in Unconsolidated Investees - Textual (Details) (USD $)	12 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Mar. 31, 2015
		investee
Schedule Of Equity Method Investments [Line Items]
Number of unconsolidated entities with direct ownership (investee)		3
Impairment of equity method investment	$236
Minimum
Schedule Of Equity Method Investments [Line Items]
Percentage of ownership from investees (percent)		15.00%
Maximum
Schedule Of Equity Method Investments [Line Items]
Percentage of ownership from investees (percent)		50.00%

Investments_in_Unconsolidated_3

Investments in Unconsolidated Investees - Balance Sheet Data (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Alliance-HNI, LLC and Subsidiaries
Schedule of financial data of unconsolidated investees, Balance Sheet Data
Current assets	$4,246	$4,721
Noncurrent assets	8,063	9,257
Current liabilities	2,855	2,773
Noncurrent liabilities	2,929	3,272
Unconsolidated Investees, Including Alliance-HNI, LLC and Subsidiaries and Austin Cyberknife
Schedule of financial data of unconsolidated investees, Balance Sheet Data
Current assets	7,494	8,687
Noncurrent assets	8,763	10,108
Current liabilities	3,822	3,760
Noncurrent liabilities	$2,965	$3,395

Investments_in_Unconsolidated_4

Investments in Unconsolidated Investees - Combined Operating Results (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Schedule of financial data of unconsolidated investees, Combined Operating Results
Earnings from unconsolidated investee	$1,163	$998
Alliance-HNI, LLC and Subsidiaries
Schedule of financial data of unconsolidated investees, Combined Operating Results
Revenues	4,164	4,106
Expenses	2,404	2,555
Net income	1,760	1,551
Earnings from unconsolidated investee	880	776
Unconsolidated Investees, Including Alliance-HNI, LLC and Subsidiaries and Austin Cyberknife
Schedule of financial data of unconsolidated investees, Combined Operating Results
Revenues	6,637	6,431
Expenses	3,336	3,535
Net income	3,301	2,896
Earnings from unconsolidated investee	$1,163	$998

Stockholders_Deficit_Details

Stockholders' Deficit (Details) (USD $)	3 Months Ended
In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance	($111,480)
Exercise of stock options (shares)	1,000	7,667
Exercise of stock options	6
Share-based payment	389
Share-based payment income tax benefit	-82
Unrealized loss on hedging transaction, net of tax	-128
Net investments in subsidiaries	16,285
Net income	6,098	4,980
Ending balance	-88,912
Common Stock
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance	107
Beginning balance (shares)	-10,713,658
Exercise of stock options (shares)	1,000
Ending balance	107
Ending balance (shares)	-10,714,658
Treasury Stock
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance			-3,138
Beginning balance (shares)			-157,973
Ending balance	-3,138		-3,138
Ending balance (shares)	-157,973		-157,973
Additional Paid-In Capital
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance	27,653
Exercise of stock options	6
Share-based payment	389
Share-based payment income tax benefit	-82
Ending balance	27,966
Accumulated Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance	-351
Unrealized loss on hedging transaction, net of tax	-128
Ending balance	-479
Accumulated Deficit
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance	-194,091
Net income	1,751
Ending balance	-192,340
Alliance HealthCare Services, Inc.
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance	-169,820
Exercise of stock options	6
Share-based payment	389
Share-based payment income tax benefit	-82
Unrealized loss on hedging transaction, net of tax	-128
Net income	1,751
Ending balance	-167,884
Noncontrolling Interest
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance	58,340
Net investments in subsidiaries	16,285
Net income	4,347
Ending balance	$78,972

Segment_Information_Textual_De

Segment Information - Textual (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Segment Reporting Information [Line Items]
Number of operating segments (segment)	3
Number of reportable segments (segment)	2
Radiology
Segment Reporting Information [Line Items]
Payments to acquire productive assets	$6,830	$2,067
Radiation Oncology
Segment Reporting Information [Line Items]
Payments to acquire productive assets	735	0
Corporate / Other
Segment Reporting Information [Line Items]
Payments to acquire productive assets	$0	$3,668

Segment_Information_Revenue_by

Segment Information - Revenue by Segment (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Summary of revenue by segment
Revenue	$109,429	$105,365
Radiology
Summary of revenue by segment
Revenue	81,387	84,638
Radiation Oncology
Summary of revenue by segment
Revenue	24,186	20,727
Other
Summary of revenue by segment
Revenue	$3,856	$0

Segment_Information_Components

Segment Information - Components of Revenue (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Summary of components of revenue
Revenue	$109,429	$105,365
MRI
Summary of components of revenue
Revenue	42,887	44,185
PET/CT
Summary of components of revenue
Revenue	31,550	33,369
Radiation Oncology
Summary of components of revenue
Revenue	24,186	20,727
Other Radiology Revenue
Summary of components of revenue
Revenue	6,950	7,084
Other revenue
Summary of components of revenue
Revenue	$3,856	$0

Segment_Information_Summary_of

Segment Information - Summary of Segment Income (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Summary of segment income
Segment income	$30,116	$32,952
Radiology
Summary of segment income
Segment income	26,374	31,010
Radiation Oncology
Summary of segment income
Segment income	11,763	9,322
Corporate / Other
Summary of segment income
Segment income	($8,021)	($7,380)

Segment_Information_Reconcilia

Segment Information - Reconciliation of Net Loss to Segment Income (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Reconciliation of Net loss to total segment income
Net income attributable to Alliance HealthCare Services, Inc.	$1,751	$1,931
Income tax (benefit) expense	1,572	1,507
Interest expense and other, net	6,018	6,238
Amortization expense	2,035	1,952
Depreciation expense	11,633	15,795
Share-based payment (included in selling, general and administrative expenses)	389	334
Severance and related costs		0
Severance and related costs	259	133
Noncontrolling interest in subsidiaries	4,347	3,049
Restructuring charges (Note 2)	255	1,025
Transaction costs	419	2
Impairment charges	76	0
Legal settlements	1,360	799
Other non-cash charges (included in other income and expense, net)	2	320
Total segment income	$30,116	$32,952

Segment_Information_Summary_of1

Segment Information - Summary of Net (Loss) Income by Segment (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Summary of net income (loss) by segment
Net (loss) income	$1,751	$1,931
Radiology
Summary of net income (loss) by segment
Net (loss) income	16,997	17,194
Radiation Oncology
Summary of net income (loss) by segment
Net (loss) income	5,024	3,426
Corporate / Other
Summary of net income (loss) by segment
Net (loss) income	($20,270)	($18,689)

Segment_Information_Summary_of2

Segment Information - Summary of Identifiable Assets (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Summary of Company's identifiable assets by segment
Identifiable assets	$551,640	$500,885
Radiology
Summary of Company's identifiable assets by segment
Identifiable assets	236,841	229,141
Radiation Oncology
Summary of Company's identifiable assets by segment
Identifiable assets	182,813	182,880
Corporate / Other
Summary of Company's identifiable assets by segment
Identifiable assets	$131,986	$88,864

Segment_Information_Summary_of3

Segment Information - Summary of Goodwill by Segment (Details) (USD $)	3 Months Ended	12 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Summary of goodwill by segment
Beginning balance	$63,864	$56,975
Goodwill acquired during the period	22,610	6,889
Impairment charges	0	0
Adjustments to goodwill during the period	0	0
Ending balance	86,474	63,864
Gross goodwill	260,718
Accumulated impairment charges	-174,244
Radiology
Summary of goodwill by segment
Beginning balance	42,166	42,166
Goodwill acquired during the period	0	0
Impairment charges	0	0
Adjustments to goodwill during the period	0	0
Ending balance	42,166	42,166
Gross goodwill	196,508
Accumulated impairment charges	-154,342
Radiation Oncology
Summary of goodwill by segment
Beginning balance	21,698	14,809
Goodwill acquired during the period	0	6,889
Impairment charges	0	0
Adjustments to goodwill during the period	0	0
Ending balance	21,698	21,698
Gross goodwill	41,600
Accumulated impairment charges	-19,902
Corporate / Other
Summary of goodwill by segment
Beginning balance	0	0
Goodwill acquired during the period	22,610	0
Impairment charges	0	0
Adjustments to goodwill during the period	0	0
Ending balance	22,610	0
Gross goodwill	22,610
Accumulated impairment charges	$0