Benefit Plans - Other Changes in Plan Assets and Benefit Obligations Recognized in Accumulated Other Comprehensive (Income) Loss (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017
Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive (Loss) Income
Net loss (gain)	$ 126	$ (126)
Total recognized in other comprehensive (loss) income	126	(126)
Total Recognized in Net Periodic Benefit Cost and Other Comprehensive (Loss) Income	$ 0	$ (79)

Amount, before tax, of gain (loss) for (increase) decrease in value of benefit obligation for change in actuarial assumptions and increase (decrease) in value of plan assets from experience different from that assumed of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=84228862&loc=d3e637-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=84228862&loc=SL7669646-108580

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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Data Type:	xbrli:monetaryItemType
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Period Type:	duration