Commitments, Guarantees and Contingent Liabilities - Florida Hurricane Catastrophe Fund and California Earthquake Authority (Details) - California Earthquake Authority - USD ($) $ in Millions	Oct. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Loss Contingencies
CEA capital balance	$ 6,010
Proceeds of revenue bonds	721
CEA existing reinsurance layer	8,260
Policy holder surcharge	1,000
Current estimated maximum CEA assessment	1,660
CEA capital balance threshold	350
CEA capital balance to be restored	350
Projected aggregate claim paying capacity	$ 17,650
Share of the CEA (as a percent)			9.80%
Maximum possible assessment		$ 162