Schedule V - Valuation and Qualifying Accounts and Reserves (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016		Dec. 31, 2015	Dec. 31, 2014
Commercial mortgage loans [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period		$ 15		$ 12	$ 8
Charged (Credited) to costs and expenses		0		7	4
Charged (Credited) to other accounts		0		0	0
Other deductions	[1]	(10)		(4)	0
Balance at end of period		5		15	12
Premiums, accounts and notes receivable [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period		75		101	43
Charged (Credited) to costs and expenses		134	[2]	(10)	53
Charged (Credited) to other accounts		(8)		(15)	5
Other deductions		(1)		(1)	0
Balance at end of period		200		75	101
Deferred tax asset valuation allowance [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period		71		49	49
Charged (Credited) to costs and expenses		21		8	21
Charged (Credited) to other accounts		(5)		14	(21)
Other deductions		0		0	0
Balance at end of period		87		71	49
Reinsurance recoverables [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period		3		4	4
Charged (Credited) to costs and expenses		0		0	0
Charged (Credited) to other accounts		0		(1)	0
Other deductions		0		0	0
Balance at end of period		$ 3		$ 3	$ 4

[1] Amounts for commercial mortgage loans primarily reflect charge-offs upon sales and repayments, as well as transfers to foreclosed real estate.

[2] Amounts for 2016 include risk corridor allowance. See Note 22 to the Consolidated Financial Statements for additional information.