Fair Value Measurements - Additional Information (Details) $ in Thousands	Dec. 31, 2018 USD ($) MutualFund	Dec. 31, 2017 USD ($)
Fair Value Assets Measured On Recurring Basis [Line Items]
Number of mutual fund investment \| MutualFund	2
Non-Recurring [Member]
Fair Value Assets Measured On Recurring Basis [Line Items]
Liabilities, fair value disclosure, non-recurring \| $	$ 0	$ 0

Fair value of financial and nonfinancial obligations.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=99377789&loc=d3e19207-110258

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