Related Party Transactions (Details 2) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Related Party Transactions
Notes due to related parties	$ 465	$ 275
Kennett | Affiliate | 6.74% Surplus Note, due 2029
Related Party Transactions
Notes due to related parties	$ 25	25
Notes payable interest rate (as a percent)	6.74%
Kennett | Affiliate | 5.06% Surplus Note, due 2035
Related Party Transactions
Notes due to related parties	$ 100	100
Notes payable interest rate (as a percent)	3.24%
Kennett | Affiliate | 6.18% Surplus Note, due 2036
Related Party Transactions
Notes due to related parties	$ 100	100
Notes payable interest rate (as a percent)	3.48%
Kennett | Affiliate | 5.93% Surplus Note, due 2038
Related Party Transactions
Notes due to related parties	$ 50	50
Notes payable interest rate (as a percent)	5.93%
Kennett | Affiliate | 4.14% Surplus Note, due 2036
Related Party Transactions
Notes due to related parties	$ 50	0
Notes payable interest rate (as a percent)	4.14%
Allstate New Jersey Insurance Company | Affiliate | 3.25% Note to Allstate New Jersey Insurance Company, due 2034
Related Party Transactions
Notes due to related parties	$ 77	0
Notes payable interest rate (as a percent)	3.25%
American Heritage Life Insurance Company | Affiliate | 3.25% Note to American Heritage Life Insurance Company, due 2034
Related Party Transactions
Notes due to related parties	$ 37	0
Notes payable interest rate (as a percent)	3.25%
Allstate Assurance Company | Affiliate | 3.25% Note to Allstate Assurance Company, due 2034
Related Party Transactions
Notes due to related parties	$ 19	0
Notes payable interest rate (as a percent)	3.25%
First Colonial Insurance Company | Affiliate | 3.25% Note to First Colonial Insurance Company, due 2034
Related Party Transactions
Notes due to related parties	$ 7	$ 0
Notes payable interest rate (as a percent)	3.25%