Represents the outstanding principal amounts of the underlying insured obligations for financial guaranty contracts, after netting out ceded contracts.

No definition available.

+ Details

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Namespace Prefix:	ago_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

The number of businesses acquired by the entity during the period.

+ References

No definition available.

+ Details

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- Definition

The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Investing Activities
-URI http://asc.fasb.org/extlink&oid=6516133

Reference 2: 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=66902209&loc=d3e3213-108585

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Acquisitions - Narrative (Details) $ in Millions			18 Months Ended
Acquisitions - Narrative (Details) $ in Millions	Jul. 01, 2016 USD ($)	Apr. 01, 2015 USD ($)	Jun. 30, 2016 Company
Business Acquisition [Line Items]
Financial guaranty companies acquired \| Company			2
Radian [Member]
Business Acquisition [Line Items]
Net par amount outstanding assumed in business acquisition		$ 13,600.0
Subsidiaries [Member] \| Radian [Member]
Business Acquisition [Line Items]
Cash purchase price		$ 804.5
Subsequent Event [Member] \| Subsidiaries [Member] \| CIFG Holding Inc. [Member]
Business Acquisition [Line Items]
Cash purchase price	$ 450.6
Subsequent Event [Member] \| CIFG Holding Inc. [Member]
Business Acquisition [Line Items]
Net par amount outstanding assumed in business acquisition	$ 4,400.0