Revenue Recognition and Contractual Adjustments - Adjustment of Transactions Revenue (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenue Recognition [Abstract]
Gross service revenues	$ 85,429	$ 114,902	$ 263,229	$ 376,857
Total contractual adjustments and discounts	(22,377)	(54,141)	(72,411)	(193,264)
Total Revenue	$ 63,052	$ 60,761	$ 190,818	$ 183,593

Aggregate revenue during the period from services rendered in the normal course of business, after deducting allowances and discounts.

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=63488584&loc=d3e20235-122688

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