The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=35755396&loc=d3e33749-111570

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.12)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The cash outflow associated with the investment in or advances to an entity in which the reporting entity shares control of the entity with another party or group.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3213-108585

+ Details

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

- Definition

Number of seats on the governing board not selected by the Company.

+ References

No definition available.

+ Details

Name:	xon_NumberOfSeatsNotSelectedByCompany
Namespace Prefix:	xon_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of seats on the governing board selected by the Company.

+ References

No definition available.

+ Details

Name:	xon_NumberOfSeatsSelectedByCompany
Namespace Prefix:	xon_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Schedule Of Investments In Joint Venture [Line Items]

+ References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
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Period Type:	duration

- Details

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Investments in Joint Ventures - Investment in OvaXon - Additional Information (Detail)	1 Months Ended
	Jan. 31, 2014 USD ($)	Dec. 31, 2015 USD ($) board_seat	Dec. 31, 2014 USD ($)
Schedule Of Investments In Joint Venture [Line Items]
Investment		$ 9,977,000	$ 3,220,000
OvaXon, LLC
Schedule Of Investments In Joint Venture [Line Items]
Capital contribution	$ 1,500,000
Membership interest	50.00%
Number of board members designated by the Company \| board_seat		2
Number of board members not designated by the Company \| board_seat		2
Investment		$ (144,000)	$ (83,000)
OvaXon, LLC \| Investor
Schedule Of Investments In Joint Venture [Line Items]
Capital contribution	$ 1,500,000
Membership interest	50.00%