Other - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Restructuring and Related Activities [Abstract]
Reorganization-related and certain other costs	$ 2.4	$ 0.2

Reorganization, Restatement, and Other Non-Recurring Cost

No definition available.

Name:	ah_ReorganizationRestatementandOtherNonRecurringCost
Namespace Prefix:	ah_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration