Fair Value Measurements (Details) - Fair Value Measurements on a Recurring Basis $ in Thousands	Jun. 30, 2018 USD ($)
Fair Value Measurements (Textual)
Cost basis of investment funds	$ 58,222
Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Deferred compensation plan assets	35,952
Liabilities:
Deferred compensation plan liabilities	72,609
Significant Other Observable Inputs (Level 2)
Assets:
Deferred compensation plan assets	27,244
Fair Value
Assets:
Deferred compensation plan assets	63,196
Liabilities:
Deferred compensation plan liabilities	$ 72,609

Fair value portion of arrangements with third parties, including, but not limited to, operating lease arrangement and arrangement in which the entity has agreed to expend funds to procure goods or services, or has agreed to commit resources to supply goods or services.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(25))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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