Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Statement [Abstract]
Revenues	$ 110,137	$ 113,375	$ 326,740	$ 338,175
Costs and expenses:
Cost of revenues, excluding depreciation and amortization	59,401	59,701	175,968	180,434
Selling, general and administrative expenses	19,811	19,229	57,934	58,571
Transaction costs	573	7	1,512	87
Severance and related costs	455	660	2,315	1,306
Impairment charges	4	4,529	240	9,396
Loss on extinguishment of debt	0	5,132	0	22,201
Depreciation expense	12,743	16,965	42,812	49,803
Amortization expense	1,961	2,151	5,870	8,856
Interest expense and other, net	6,208	8,156	18,570	31,481
Other income, net	(602)	(748)	(933)	(2,035)
Total costs and expenses	100,554	115,782	304,288	360,100
(Loss) income before income taxes, earnings from unconsolidated investees, and noncontrolling interest	9,583	(2,407)	22,452	(21,925)
Income tax (benefit) expense	2,948	(2,392)	6,256	(9,725)
Earnings from unconsolidated investees	(1,219)	(1,347)	(3,459)	(4,489)
Net income (loss)	7,854	1,332	19,655	(7,711)
Less: Net income attributable to noncontrolling interest	(3,843)	(3,402)	(10,928)	(9,741)
Net (loss) income attributable to Alliance HealthCare Services, Inc.	4,011	(2,070)	8,727	(17,452)
Comprehensive (loss) income, net of taxes:
Net (loss) income attributable to Alliance HealthCare Services, Inc.	4,011	(2,070)	8,727	(17,452)
Unrealized (loss) gain on hedging transactions, net of taxes	50	(154)	(165)	(426)
Comprehensive (loss) income, net of taxes	$ 4,061	$ (2,224)	$ 8,562	$ (17,878)
(Loss) income per common share attributable to Alliance HealthCare Services, Inc.:
Basic (dollars per share)	$ 0.37	$ (0.19)	$ 0.82	$ (1.64)
Diluted (dollars per share)	$ 0.37	$ (0.19)	$ 0.80	$ (1.64)
Weighted-average number of shares of common stock and common stock equivalents:
Basic (shares)	10,710	10,639	10,683	10,632
Diluted (shares)	10,851	10,639	10,864	10,632