Revenue Recognition and Contractual Adjustments - Adjustment of Transactions Revenue (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenue Recognition [Abstract]
Gross service revenues	$ 93,862	$ 129,235	$ 177,800	$ 261,955
Total contractual adjustments and discounts	(27,772)	(66,106)	(50,033)	(139,123)
Total Revenue	$ 66,090	$ 63,129	$ 127,767	$ 122,832

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