Income Taxes - Reconciliation of income taxes at the statutory rate to the provision for income taxes (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Earnings before income taxes (“EBT”)	$ 413	$ 174
Income taxes at statutory rate	87	37
Effect of tax exempt interest	(4)	(3)
Effect of dividends received deduction	(1)	(1)
Effect of stock-based compensation	(2)	(5)
Effect of nondeductible expenses	2	2
Effect of change in valuation allowance	2	0
Effect of foreign operations	0	3
Effect of other income tax reconciliation	3	0
Provision for income taxes as shown on the Statement of Earnings	$ 87	$ 33
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Income taxes at statutory rate as a percentage of EBT	21.00%	21.00%
Effect of tax exempt interest as a percentage of EBT	(1.00%)	(2.00%)
Effect of dividends received deduction as a percentage of EBT	(0.00%)	(0.00%)
Effect of stock-based compensation as a percentage of EBT	0.00%	(3.00%)
Effect of nondeductible expenses as a percentage of EBT	0.00%	1.00%
Effect of change in valuation allowance as a percentage of EBT	0.00%	0.00%
Effect of foreign operations as a percentage of EBT	0.00%	2.00%
Effect of other income tax reconciliation as a percentage of EBT	1.00%	0.00%
Provision for income taxes as shown on the Statement of Earnings as a percentage of EBT	21.00%	19.00%