Aggregate dividends declared during the period for each share of common stock outstanding.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section S99
-Paragraph 1
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Unrecognized cost of unvested share-based compensation awards.

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-Publisher FASB
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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

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Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions		6 Months Ended
	Jul. 10, 2018	Jun. 30, 2018	Jun. 30, 2017
Share-based Compensation [Abstract]
Options vesting and exercisable period, maximum		8 years
Options termination period		9 years
Total stock-based compensation expense		$ 2.5	$ 2.8
Total unrecognized stock-based compensation expense		$ 16.0
Weighted average period over which total unrecognized stock-based compensation expense will be recognized		4 years 3 months 7 days
Subsequent Event
Subsequent Event [Line Items]
Dividend declared (in dollars per share)	$ 0.4