v2.4.0.8

Redeemable Convertible Preferred Stock and Shareholders' Deficit - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	1 Months Ended	12 Months Ended
	Aug. 13, 2013	Dec. 31, 2012
Temporary Equity [Line Items]
Redemption price of arrearage amount	$ 68,850	$ 50,549
Redeemable convertible preferred stock	79,705,130
Series A Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Dividend rate per annum		6.00%
Dividend declared		$ 0
Redemption price of arrearage amount		556
Series B Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Dividend rate per annum		6.00%
Dividend declared		$ 0
Redemption price of arrearage amount		209
Series B-1 Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Dividend rate per annum		6.00%
Dividend declared		$ 0
Redemption price of arrearage amount		380
Series C Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Dividend rate per annum		6.00%
Dividend declared		$ 0
Redemption price of arrearage amount		2,162
Series C-1 Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Dividend rate per annum		6.00%
Dividend declared		$ 0
Redemption price of arrearage amount		9,222
Series C-2 Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Dividend rate per annum		6.00%
Dividend declared		$ 0
Redemption price of arrearage amount		9,614
Series C-3 Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Dividend rate per annum		6.00%
Dividend declared		$ 0
Redemption price of arrearage amount		4,819
Series D Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Dividend rate per annum		6.00%
Dividend declared		$ 0
Redemption price of arrearage amount		9,411
Series E Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Dividend rate per annum		6.00%
Dividend declared		$ 0
Redemption price of arrearage amount		$ 14,086

X

- Definition

The number of new shares issued in the conversion of stock in a noncash (or part noncash) transaction. Noncash is defined as transactions during a period that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 5

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4332-108586



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4313-108586



Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=6367179&loc=d3e4304-108586

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

X

- Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Aggregate amount of cumulative dividends on redeemable convertible preferred stock in arrears.

+ References

No definition available.

+ Details

Name:	xon_TemporaryEquityAmountOfDividendsInArrears
Namespace Prefix:	xon_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Rate per annum to which holders of the redeemable convertible preferred stock shall be entitled to receive dividends, when and if declared.

+ References

No definition available.

+ Details

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Namespace Prefix:	xon_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Aggregate dividends declared during the period for each share of redeemable convertible preferred stock outstanding.

+ References

No definition available.

+ Details

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Namespace Prefix:	xon_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration