Insurance (Separate Accounts - Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule Separate Accounts [Line Items]
Separate account assets	$ 175,556	$ 205,001
Gain (Loss) Recognized on Assets Transferred to Separate Account	$ 0	$ 0	$ 0
Participating Insurance, Percentage of Gross Insurance in Force	3.00%	3.00%
Funding Agreements and Participating Close Out Contracts Included in Separate Accounts with a Guaranteed Minimum Return or Account Value
Schedule Separate Accounts [Line Items]
Average interest rate credited on separate accounts with a guaranteed minimum return or account value	2.60%	2.34%
Pass Through Separate Accounts
Schedule Separate Accounts [Line Items]
Separate account assets	$ 129,200	$ 148,200
Separate Accounts With Minimum Return Or Account Value
Schedule Separate Accounts [Line Items]
Separate account assets	$ 46,400	$ 56,800