Income Taxes - Effective Income Tax Rate (Details)	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Reconciliation between the U.S. corporate income tax rate and the effective income tax rate from continuing operations
U.S. corporate income tax rate (as a percent)	21.00%	21.00%	21.00%	21.00%
Dividends received deduction (as a percent)	(4.00%)	(3.00%)	(5.00%)	(3.00%)
Tax credits (as a percent)	(3.00%)	(3.00%)	(2.00%)	(3.00%)
Impact of equity method presentation (as a percent)	(1.00%)	(1.00%)	(1.00%)	(1.00%)
Impact of the Tax Cuts and Jobs Act (as a percent)		(4.00%)		(3.00%)
State income taxes (as a percent)		1.00%	1.00%	1.00%
Other income tax rate impacts (as a percent)				(1.00%)
Effective income tax rate (as a percent)	13.00%	11.00%	14.00%	11.00%

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to changes in the income tax rates.

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