Statements of Cash Flows - Additional Information (Details) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016
Supplemental Cash Flow Elements [Abstract]
Excess tax expense from stock-based compensation arrangements being reclassified from financing activities to other operating activities, net		$ 126
Taxes paid for shares directly withheld being reclassified from other operating activities, net to financing activities	$ 1,639	$ 949

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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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration