Recently Adopted Accounting Standards - Additional Information (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Feb. 29, 2016
Operating lease assets	$ 44,251	$ 0
Operating lease liabilities	$ 6,859	$ 0
Accounting Standards Update 2016-02 [Member]
Operating lease assets			$ 45,800
Operating lease liabilities			$ 47,200

Present value of lessee's discounted obligation for lease payments from operating lease, classified as current.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977

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