Financing Receivables (Credit Quality Information Tables) (Details 3) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2018	Dec. 31, 2015
Commercial mortgage loans
Total loans, gross	$ 3,275		$ 3,263
Less: allowance for loan losses	26	$ 29	24	$ 32
Residential and Consumer Portfolio Segment [Member]
Commercial mortgage loans
Financing Receivable, Significant Sales	267	$ 271
Commercial mortgage loans [Member]
Commercial mortgage loans
Total loans, gross	2,775		2,715
Less: allowance for loan losses	19		19
Total loans, net	$ 2,756		$ 2,696
Percentage of gross commercial mortgage loans	100.00%		100.00%
Commercial mortgage loans [Member] | Apartments [Member]
Commercial mortgage loans
Total loans, gross	$ 566		$ 621
Percentage of gross commercial mortgage loans	20.00%		23.00%
Commercial mortgage loans [Member] | Hotel [Member]
Commercial mortgage loans
Total loans, gross	$ 40		$ 43
Percentage of gross commercial mortgage loans	1.00%		1.00%
Commercial mortgage loans [Member] | Industrial [Member]
Commercial mortgage loans
Total loans, gross	$ 476		$ 453
Percentage of gross commercial mortgage loans	17.00%		17.00%
Commercial mortgage loans [Member] | Mixed Use [Member]
Commercial mortgage loans
Total loans, gross	$ 44		$ 54
Percentage of gross commercial mortgage loans	2.00%		2.00%
Commercial mortgage loans [Member] | Office
Commercial mortgage loans
Total loans, gross	$ 492		$ 435
Percentage of gross commercial mortgage loans	18.00%		16.00%
Commercial mortgage loans [Member] | Retail
Commercial mortgage loans
Total loans, gross	$ 937		$ 897
Percentage of gross commercial mortgage loans	34.00%		33.00%
Commercial mortgage loans [Member] | Other
Commercial mortgage loans
Total loans, gross	$ 220		$ 212
Percentage of gross commercial mortgage loans	8.00%		8.00%
Commercial mortgage loans [Member] | East North Central [Member]
Commercial mortgage loans
Total loans, gross	$ 215		$ 216
Percentage of gross commercial mortgage loans	8.00%		8.00%
Commercial mortgage loans [Member] | East South Central [Member]
Commercial mortgage loans
Total loans, gross	$ 90		$ 107
Percentage of gross commercial mortgage loans	3.00%		4.00%
Commercial mortgage loans [Member] | Middle Atlantic [Member]
Commercial mortgage loans
Total loans, gross	$ 192		$ 187
Percentage of gross commercial mortgage loans	7.00%		7.00%
Commercial mortgage loans [Member] | Mountain [Member]
Commercial mortgage loans
Total loans, gross	$ 256		$ 237
Percentage of gross commercial mortgage loans	9.00%		9.00%
Commercial mortgage loans [Member] | New England [Member]
Commercial mortgage loans
Total loans, gross	$ 74		$ 62
Percentage of gross commercial mortgage loans	3.00%		2.00%
Commercial mortgage loans [Member] | Pacific [Member]
Commercial mortgage loans
Total loans, gross	$ 812		$ 814
Percentage of gross commercial mortgage loans	29.00%		30.00%
Commercial mortgage loans [Member] | South Atlantic [Member]
Commercial mortgage loans
Total loans, gross	$ 768		$ 731
Percentage of gross commercial mortgage loans	28.00%		27.00%
Commercial mortgage loans [Member] | West North Central [Member]
Commercial mortgage loans
Total loans, gross	$ 235		$ 213
Percentage of gross commercial mortgage loans	8.00%		8.00%
Commercial mortgage loans [Member] | West South Central [Member]
Commercial mortgage loans
Total loans, gross	$ 133		$ 148
Percentage of gross commercial mortgage loans	5.00%		5.00%