Reserves for Insurance Losses and Loss Adjustment Expenses Reserves for Insurance Losses and Loss Adjustment Expenses (Short-duration Contracts, Schedule of Historical Claims Duration) (Details)	Dec. 31, 2019
Short-duration Insurance Contracts, Liability for Unpaid Claims and Allocated Claim Adjustment Expense, Net [Abstract]
Percentage payout of incurred claims, Year One	92.60%
Percentage payout of incurred claims, Year Two	6.60%
Percentage payout of incurred claims, Year Three	0.40%
Percentage payout of incurred claims, Year Four	0.20%
Percentage payout of incurred claims, Year Five	0.10%
Percentage payout of incurred claims, Year Six	0.10%
Percentage payout of incurred claims, Year Seven	0.10%
Percentage payout of incurred claims, Year Eight	0.00%