DEFERRED POLICY ACQUISITION COSTS AND VALUE OF BUSINESS ACQUIRED (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Balances and changes in DAC
Balance, beginning of period	$ 572,328	$ 288,611
Capitalization of commissions, sales, and issue expenses	333,250	327,938
Amortization	(52,559)	(48,286)
Change due to unrealized investment gains and losses	(15,234)	4,065
Balance, end of period	837,785	572,328
Balances and changes in VOBA
Balance, beginning of period	1,447,501	1,270,197
Acquisitions	0	285,092
Amortization	(25,662)	(100,778)
Change due to unrealized investment gains and losses	(60,047)	(7,010)
Balance, end of period	1,361,792	$ 1,447,501
Expected amortization of VOBA for the next five years
2018	122,802
2019	118,196
2020	103,120
2021	90,544
2022	$ 83,333