Revenue Recognition and Contractual Adjustments - Adjustment of Transactions Revenue (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenue Recognition [Abstract]
Gross service revenues	$ 56,702	$ 57,805	$ 110,333	$ 99,004
Total contractual adjustments and discounts	(32,332)	(37,135)	(62,937)	(60,152)
Net revenues	$ 24,370	$ 20,670	$ 47,396	$ 38,852

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

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