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Insurance in Force (Schedule Of Geographical Distribution Of Insurance In Force) (Detail) - USD ($) $ in Billions	Dec. 31, 2017	Dec. 31, 2016
Insurance in Force	$ 154.9	$ 235.9
% of Insurance in Force	100.00%	100.00%
California [Member]
Insurance in Force	$ 30.3	$ 42.7
% of Insurance in Force	19.60%	18.10%
Illinois [Member]
Insurance in Force	$ 13.1	$ 15.4
% of Insurance in Force	8.50%	6.50%
New York [Member]
Insurance in Force	$ 9.3	$ 16.6
% of Insurance in Force	6.00%	7.00%
Puerto Rico [Member]
Insurance in Force	$ 8.2	$ 8.6
% of Insurance in Force	5.30%	3.60%
New Jersey [Member]
Insurance in Force	$ 7.6	$ 11.5
% of Insurance in Force	4.90%	4.90%
Texas [Member]
Insurance in Force	$ 6.1	$ 9.1
% of Insurance in Force	3.90%	3.90%
Hawaii [Member]
Insurance in Force	$ 4.5	$ 5.2
% of Insurance in Force	2.90%	2.20%
Virginia [Member]
Insurance in Force	$ 4.2	$ 5.2
% of Insurance in Force	2.70%	2.20%
Florida [Member]
Insurance in Force	$ 3.8	$ 8.7
% of Insurance in Force	2.50%	3.70%
Oregon [Member]
Insurance in Force	$ 3.6	$ 4.2
% of Insurance in Force	2.30%	1.80%
Sub-Total Insurance In Force [Member]
Insurance in Force	$ 90.7	$ 127.2
% of Insurance in Force	58.60%	53.90%
Nationally Diversified [Member]
Insurance in Force	$ 15.7	$ 20.4
% of Insurance in Force	10.10%	8.60%
Other States [Member]
Insurance in Force	$ 37.0	$ 57.9
% of Insurance in Force	23.90%	24.60%
United States [Member]
Insurance in Force	$ 143.4	$ 205.5
% of Insurance in Force	92.60%	87.10%
Internationally Diversified [Member]
Insurance in Force	$ 0.4	$ 0.5
% of Insurance in Force	0.30%	0.20%
Country Specific [Member]
Insurance in Force	$ 11.1	$ 29.9
% of Insurance in Force	7.10%	12.70%
Non-United States [Member]
Insurance in Force	$ 11.5	$ 30.4
% of Insurance in Force	7.40%	12.90%

X

- Definition

Represents the gross outstanding insured contractual payments for each caterory as a percentage of the total outstanding insured contractual payments.

+ References

No definition available.

+ Details

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X

- Definition

Represents the amount of insured contractual payments (principal and interest) outstanding on the underlying insured obligations for financial guaranty contracts, gross of ceded contracts.

+ References

No definition available.

+ Details

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- Details

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