Commitments and Contingencies (Detail)	12 Months Ended
Dec. 31, 2018
Pending Litigation
Loss Contingencies [Line Items]
Loss contingency, inestimable loss	<div style="font-family:Times New Roman;font-size:10pt;"><div style="line-height:120%;padding-top:12px;text-align:left;font-size:10pt;"><font style="font-family:inherit;font-size:10pt;">For matters for which we have not recorded an accrued liability, we are unable to estimate a range of possible loss because the issues involved have not been fully developed through pleadings and discovery.</font></div></div>

Explanation as to why an estimate of a specified contingent loss cannot be made, resulting in disclosure without accrual.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 9
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14557-108349

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14435-108349

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Balance Type:	na
Period Type:	duration