Selected Statement of Operations Data - Additional Information (Detail)	12 Months Ended
Dec. 31, 2017 Customer Segment	Dec. 31, 2016 Customer	Dec. 31, 2015 Customer shares
Segment Reporting [Abstract]
Number of reportable segments \| Segment	3
Percentage of maximum revenue from customer	10.00%	10.00%	10.00%
Number of individual customers accounted for more than 10% of company's revenues \| Customer	0	0	0
Aggregate amounts of ordinary shares \| shares			13,015

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration