Property and Casualty Insurance Reserves Historical Claims Duration (Details)	Dec. 31, 2018
Preferred Personal Automobile Liability Insurance [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	38.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	68.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	82.40%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	92.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	97.10%
Preferred Personal Automobile Physical Damage Insurance [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	98.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	100.40%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	100.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	100.00%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	100.10%
Non-standard Personal Automobile Liability Insurance [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	44.70%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	81.40%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	92.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	96.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	97.80%
Non-standard Personal Automobile Physical Damage Insurance [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	94.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	100.70%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	100.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	100.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	100.30%
Commercial Automobile Insurance-Liability [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	30.90%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	61.80%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	78.60%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	88.60%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	97.00%
Commercial Automobile Insurance - Physical Damage [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	93.50%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	100.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	100.20%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	100.30%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	100.00%
Homeowners [Member]
Short-duration Insurance Contracts, Historical Claims Duration [Line Items]
Short-duration Insurance Contracts, Historical Claims Duration, Year One	69.10%
Short-duration Insurance Contracts, Historical Claims Duration, Year Two	93.90%
Short-duration Insurance Contracts, Historical Claims Duration, Year Three	96.60%
Short-duration Insurance Contracts, Historical Claims Duration, Year Four	98.60%
Short-duration Insurance Contracts, Historical Claims Duration, Year Five	99.30%