Outstanding Exposure - Puerto Rico Gross Par and Gross Debt Service Outstanding (Details) - USD ($) $ in Millions		Jun. 30, 2015	Dec. 31, 2014
Schedule of Insured Financial Obligations [Line Items]
Gross Debt Service Outstanding		$ 611,993	$ 646,722
Puerto Rico [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding		6,222	6,035
Gross Debt Service Outstanding		10,260	10,074
Subject to the Terms of the Recovery Act [Member] | Puerto Rico [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding	[1]	3,135	3,058
Gross Debt Service Outstanding	[1]	5,408	5,326
Not Subject to the Terms of the Recovery Act [Member] | Puerto Rico [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross par outstanding		3,087	2,977
Gross Debt Service Outstanding		$ 4,852	$ 4,748

[1] On February 6, 2015, the U.S. District Court for the District of Puerto Rico ruled that the Recovery Act is preempted by the Federal Bankruptcy Code and is therefore void, and on July 6, 2015, the U.S. Court of Appeals for the First Circuit upheld that ruling.