Outstanding Insurance Exposure - Debt Service Outstanding (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Schedule of Insured Financial Obligations [Line Items]
Gross Debt Service Outstanding	$ 375,776	$ 375,080
Net debt service outstanding	374,130	371,586
Public Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross Debt Service Outstanding	363,497	361,511
Net debt service outstanding	362,361	358,438
Structured Finance [Member]
Schedule of Insured Financial Obligations [Line Items]
Gross Debt Service Outstanding	12,279	13,569
Net debt service outstanding	$ 11,769	$ 13,148