Insurance (Obligations Under Funding Agreements - Narrative) (Details) - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Insurance [Abstract]
Funding agreements issued to certain SPEs	$ 41.8	$ 42.7	$ 39.7
Funding agreements repaid to certain SPEs	43.7	41.4	$ 38.5
Outstanding funding agreements to certain SPEs	$ 32.3	$ 34.2