Share Based Compensation - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013 Y
Angel. Com
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration of grant date	10
Cash payment for termination of incentive plan	$ 8.0
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company's stock plan term (in years)	5 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Company's stock plan term (in years)	10 years

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.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration