Segment Information (Reconciliation of Net Loss to Segment Income) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Reconciliation of Net loss to total segment income
Net loss attributable to Alliance HealthCare Services, Inc.	$ (12,964)	$ (801)	$ (15,382)	$ (5,623)
Income tax (benefit) expense	(7,195)	(2,427)	(7,333)	(5,069)
Interest expense and other, net	11,053	13,679	23,325	27,367
Amortization expense	2,911	3,994	6,705	8,006
Depreciation expense	16,322	20,693	32,838	42,138
Share-based payment (included in selling, general and administrative expenses)	329	(840)	735	36
Noncontrolling interest in subsidiaries	3,509	2,728	6,339	4,978
Restructuring charges (Note 2)	1,890	873	3,363	2,995
Transaction costs	0	20	80	379
Impairment charges	4,867	0	4,867	0
Loss on extinguishment of debt	17,069	0	17,069	0
Other non-recurring charges (included in selling, general and administrative expenses	633	0	950	0
Other non-cash charges (included in other income and expense, net)	161	1,489	190	1,959
Total segment income	$ 38,585	$ 39,408	$ 73,746	$ 77,166