Reconciliation of Beginning and Ending Liability Balances for Restructuring Charges (Detail) $ in Thousands	9 Months Ended
Sep. 30, 2017 USD ($)
Restructuring Cost and Reserve [Line Items]
Accrual - Beginning balance	$ 1,376
Costs paid or settled	(1,014)
Accrual - Ending balance	362
Twenty Sixteen Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Accrual - Beginning balance	209
Costs paid or settled	(209)
Twenty Fifteen Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Accrual - Beginning balance	1,167
Costs paid or settled	(805)
Accrual - Ending balance	$ 362

Carrying amount as of the balance sheet date of known and estimated obligations associated with exit from or disposal of business activities or restructurings pursuant to a duly authorized plan, which are expected to be paid in the next twelve months or in the normal operating cycle if longer. Costs of such activities include those for one-time termination benefits, termination of an operating lease or other contract, consolidating or closing facilities, relocating employees, and costs associated with an ongoing benefit arrangement, but excludes costs associated with the retirement of a long-lived asset.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 5.P.4(b)(2))
-URI http://asc.fasb.org/extlink&oid=27011515&loc=d3e140904-122747

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869

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