INVESTMENTS - Other Investments (Details) - USD ($) $ in Millions		Sep. 30, 2018	Dec. 31, 2017
Investment Holdings [Line Items]
Other investments	[1]	$ 7,009	$ 3,402
Transitional real estate loans
Investment Holdings [Line Items]
Other investments		4,128	1,235
Commercial mortgage loans
Investment Holdings [Line Items]
Other investments		1,026	908
Middle market loans
Investment Holdings [Line Items]
Other investments		1,363	859
Policy loans
Investment Holdings [Line Items]
Other investments		223	210
Short-term investments
Investment Holdings [Line Items]
Other investments		2	57
Other investments
Investment Holdings [Line Items]
Other investments		$ 267	$ 133

[1] Includes $5,388 in 2018 and $2,341 in 2017 of loan receivables and limited partnerships from consolidated variable interest entities