Income Taxes - Effective Income Tax Rate (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Reconciliation between the U.S. corporate income tax rate and the effective income tax rate from continuing operations
U.S. corporate statutory income tax rate (as a percent)	35.00%	35.00%	35.00%	35.00%
Dividends received deduction (as a percent)	(12.00%)	(10.00%)	(11.00%)	(9.00%)
Impact of equity method presentation (as a percent)	(3.00%)	(3.00%)	(3.00%)	(2.00%)
Tax credits (as a percent)	(3.00%)	(2.00%)	(3.00%)	(2.00%)
Other income tax rate impacts (as a percent)	(3.00%)	(2.00%)	(4.00%)	(5.00%)
Effective income tax rate (as a percent)	14.00%	18.00%	14.00%	17.00%