MONY CLOSED BLOCK OF BUSINESS - Summary of Financial Information of the Policyholder Dividend Obligation (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Closed block liabilities
Future policy benefits, policyholders’ account balances and other policyholder liabilities	$ 5,814,527	$ 5,896,355
Policyholder dividend obligation	136,004	31,932	$ 264,107	$ 0
Other liabilities	76,176	40,007
Total closed block liabilities	6,026,707	5,968,294
Closed block assets
Fixed maturities, available-for-sale, at fair value	4,549,322	4,440,105
Mortgage loans on real estate	130,521	201,088
Policy loans	707,293	712,959
Cash	148,612	108,270
Other assets	141,740	135,794
Total closed block assets	5,677,488	5,598,216
Excess of reported closed block liabilities over closed block assets	349,219	370,078
Portion of above representing accumulated other comprehensive income:
Net unrealized investment gains (losses) net of policyholder dividend obligation: $(55,231) and $(197,450); and net of income tax: $19,331 and $69,107	0	0
Future earnings to be recognized from closed block assets and closed block liabilities	349,219	370,078
Net unrealized investment gains (losses) allocated to policyholder dividend obligation, net of deferred tax benefits	(55,231)	(197,450)
Net unrealized investment gains (losses), income tax	$ 19,331	$ 69,107