Schedule V - Valuation Allowances and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for reinsurance recoverables
Valuation allowances and qualifying accounts
Balance as of beginning of period	$ 84	$ 80	$ 95
Additions, Charged to costs and expenses	(10)	5	(15)
Additions, Other additions	0	0	0
Deductions	4	1	0
Balance as of end of period	70	84	80
Allowance for premium installment receivable
Valuation allowances and qualifying accounts
Balance as of beginning of period	84	90	83
Additions, Charged to costs and expenses	109	107	107
Additions, Other additions	0	0	0
Deductions	116	113	100
Balance as of end of period	77	84	90
Allowance for deferred tax assets
Valuation allowances and qualifying accounts
Balance as of beginning of period	0	0	0
Additions, Charged to costs and expenses	0	0	0
Additions, Other additions	0	0	0
Deductions	0	0	0
Balance as of end of period	0	0	0
Allowance for estimated losses on mortgage loans
Valuation allowances and qualifying accounts
Balance as of beginning of period	3	3	8
Additions, Charged to costs and expenses	1	0	(4)
Additions, Other additions	0	0	0
Deductions	1	0	1
Balance as of end of period	$ 3	$ 3	$ 3