Segment Information - Additional Information (Details)	3 Months Ended	12 Months Ended
Mar. 31, 2014 segment	Dec. 31, 2014 customer segment	Dec. 31, 2013 customer	Dec. 31, 2012 customer
Segment Reporting Information [Line Items]
Number of segments	2us-gaap_NumberOfOperatingSegments	2us-gaap_NumberOfOperatingSegments
Number of reportable segments		2us-gaap_NumberOfReportableSegments
Number of significant customers that accounted for more than 10% of accounts receivables		0omcl_ConcentrationRiskCustomerNumber	0omcl_ConcentrationRiskCustomerNumber	0omcl_ConcentrationRiskCustomerNumber

Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

No definition available.

Name:	us-gaap_NumberOfOperatingSegments
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration