Summary of Significant Accounting Policies - Adjustment of Transactions Revenue (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenue Recognition [Abstract]
Gross Service Revenues	$ 224,460us-gaap_SalesRevenueServicesGross	$ 173,784us-gaap_SalesRevenueServicesGross	$ 157,591us-gaap_SalesRevenueServicesGross
Total Contractual Adjustments and Discounts	(137,391)neo_ContractualAdjustmentsAndDiscounts	(107,317)neo_ContractualAdjustmentsAndDiscounts	(97,724)neo_ContractualAdjustmentsAndDiscounts
Net Service Revenues	$ 87,069us-gaap_SalesRevenueServicesNet	$ 66,467us-gaap_SalesRevenueServicesNet	$ 59,867us-gaap_SalesRevenueServicesNet

Aggregate revenue during the period for services rendered in the normal course of business (before deducting allowances and discounts) which are not otherwise defined in the taxonomy.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1(d))

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

Name:	us-gaap_SalesRevenueServicesGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration