Amount of expenses for special or contractual termination benefits provided to current employees involuntarily terminated under a benefit arrangement associated exit or disposal activities pursuant to an authorized plan. Excludes expenses related to one-time termination benefits, a discontinued operation or an asset retirement obligation.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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Name:	us-gaap_SeveranceCosts1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Restructuring - Additional Information (Detail) - USD ($) $ in Millions		3 Months Ended	12 Months Ended
	Dec. 31, 2018	Jun. 30, 2019	Dec. 31, 2018
Restructuring Cost And Reserve [Line Items]
Restructuring, initiation date			Dec. 11, 2018
Accrual and related expense related to severance benefits	$ 0.3		$ 0.3
Scenario Forecast [Member]
Restructuring Cost And Reserve [Line Items]
Employee severance and related costs		$ 0.8