Investments (Collectively Significant Equity Method Investments - Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Equity Method Investment, Summarized Financial Information, Gross Profit (Loss)
Carrying Value of investments accounted for under the equity method		$ 14,700
Unfunded commitments for investments accounted for under the equity method		5,300
Total assets for investments accounted for under the equity method		529,100	$ 505,600
Total liabilities for investments accounted for under the equity method		65,500	68,900
Net Income (loss) for investments accounted for under the equity method		$ 52,500	$ 37,900	$ 26,800
Aggregate Net income Exceeded Stated Percentage Of The Pre Tax Income (Loss) From Continuing Operations	10.00%	10.00%
Brighthouse Financial, Inc
Equity Method Investment, Summarized Financial Information, Gross Profit (Loss)
Net Income (loss) for investments accounted for under the equity method				$ 270