Income Taxes - Additional Information (Detail) - USD ($)	Dec. 31, 2016	Dec. 31, 2015
Income Taxes [Line Items]
Deferred tax amounts, valuation allowance recorded	$ 0	$ 0
Uncertain tax positions	$ 0	$ 0
Minimum [Member]
Income Taxes [Line Items]
Tax position measured if more-likely-than-not threshold is exceeded, percentage	50.00%

Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=65882285&loc=d3e32537-109319

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