Accounting Policies - New Accounting Standards (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2017	Sep. 30, 2016
Accounting Policies [Abstract]
Proceeds and Excess Tax Benefit from Share-based Compensation	$ 300	$ 1,200
Excess Tax Benefits from Share-Based Compensation	$ 300	1,170	$ 0
Payments Related to Tax Withholding for Share-based Compensation		$ 2,283	$ 1,975

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://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3291-108585

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