Stockholders' Deficit (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance			$ (136,617)
Exercise of stock options (shares)			72,794	24,500
Exercise of stock options			768
Forfeit of restricted stock			0
Issuance of restricted stock			(140)
Share-based payment			1,117
Unrealized gain on hedging transaction, net of tax			(165)
Net contributions (distributions)			(11,937)
Net (loss) income	7,854	1,332	19,655	(7,711)
Ending balance	(127,319)		(127,319)
Common Stock
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance			524
Beginning balance (shares)			10,667,136
Exercise of stock options (shares)			72,794
Exercise of stock options			1
Forfeit of restricted stock (shares)			26,272
Forfeit of restricted stock			0
Issuance of restricted stock (shares)			0
Ending balance	525		525
Ending balance (shares)	10,713,658		10,713,658
Treasury Stock
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance			(2,998)
Beginning balance (shares)			(144,921)
Issuance of restricted stock			(140)
Issuance of restricted stock (shares)			(5,323)
Ending balance	(3,138)		(3,138)
Ending balance (shares)	(150,244)		(150,244)
Additional Paid-In Capital
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance			23,521
Exercise of stock options			767
Share-based payment			1,117
Net contributions (distributions)			1,652
Ending balance	27,057		27,057
Accumulated Comprehensive Income (Loss)
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance			(82)
Unrealized gain on hedging transaction, net of tax			(165)
Ending balance	(247)		(247)
Accumulated Deficit
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance			(204,709)
Net (loss) income			8,727
Ending balance	(195,982)		(195,982)
Alliance HealthCare Services, Inc.
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance			(183,744)
Exercise of stock options			768
Forfeit of restricted stock			0
Issuance of restricted stock			(140)
Share-based payment			1,117
Unrealized gain on hedging transaction, net of tax			(165)
Net contributions (distributions)			1,652
Net (loss) income			8,727
Ending balance	(171,785)		(171,785)
Noncontrolling Interest
Increase (Decrease) in Stockholders' Deficit [Roll Forward]
Beginning balance			47,127
Net contributions (distributions)			(13,589)
Net (loss) income			10,928
Ending balance	$ 44,466		$ 44,466