Stockholders' Equity (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017
Stockholders' Equity Attributable to Parent [Abstract]
Treasury Stock Purchase Plan	$ 40,000
Treasury Stock Purchase Plan Remaining Available	$ 7,200
Shares Paid for Tax Withholding for Share Based Compensation	25,745
Payments Related to Tax Withholding for Share-based Compensation	$ 6,119	$ 3,951

Amount of cash outflow to satisfy an employee's income tax withholding obligation as part of a net-share settlement of a share-based award.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3291-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 25
-Paragraph 19A
-URI http://asc.fasb.org/extlink&oid=107668666&loc=SL79513924-113897

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