Expected forfeitures for employee service share based compensation nonvested awards compensation cost not yet recognized.

No definition available.

+ Details

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Namespace Prefix:	inst_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

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Period Type:	duration

- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

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.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Details

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Data Type:	na
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- Details

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Namespace Prefix:
Data Type:	na
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Subsequent Events - Additional Information (Details) - USD ($)	1 Months Ended	9 Months Ended	12 Months Ended
	Oct. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Subsequent Event [Line Items]
Weighted-average period for unrecognized compensation cost expected to be recognized		3 years	3 years
Restricted Stock Units
Subsequent Event [Line Items]
Shares granted		1,024,000
Restricted Stock Units \| Subsequent Event
Subsequent Event [Line Items]
Shares granted	90,237
Net of estimated forfeitures for unrecognized non vested stock based compensation	$ 2,008,000
Weighted-average period for unrecognized compensation cost expected to be recognized	3 years 10 months 24 days