OPERATING SEGMENTS (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Summarized financial information for the company's segments
Revenues	$ 1,681,993			$ 1,269,963			$ 4,497,275	$ 3,503,118
Pre-tax Adjusted Operating Income (Loss)	100,162			125,794			313,815	275,829
Realized gains (losses) on investments and derivatives	139,679			(30,624)			288,476	(97,829)
Income before income tax	239,841			95,170			602,291	178,000
Income tax expense	(49,417)			(16,646)			(115,355)	(28,933)
Net income	190,424	$ 154,414	$ 142,098	78,524	$ 52,268	$ 18,275	486,936	149,067
Adjusted operating income tax expense	(20,085)			(23,077)			(54,775)	(49,477)
After-tax adjusted operating income	80,077			102,717			259,040	226,352
Income tax (expense) benefit on adjustments	(29,332)			6,431			(60,580)	20,544
Realized investment (losses) gains:
Derivative financial instruments	42,286			(26,710)			(86,288)	37,176
All other investments	88,217			(20,156)			317,254	(157,350)
Net impairment losses recognized in earnings	(10,818)			(14)			(14,658)	(3,664)
Less: related amortization	(6,205)			(5,859)			(37,406)	5,060
Less: VA GLWB economic cost	(13,789)			(10,397)			(34,762)	(31,069)
Operating Segment Assets
Investments and other assets	113,877,196						113,877,196		$ 84,918,374
DAC and VOBA	3,427,590						3,427,590		3,026,330
Other Intangible Assets, Net	595,819						595,819		612,854
Goodwill	825,511						825,511		825,511
Total assets	118,726,116						118,726,116		89,383,069
Life Marketing
Summarized financial information for the company's segments
Revenues	441,108			407,708			1,274,496	1,195,074
Pre-tax Adjusted Operating Income (Loss)	(24,669)			3,647			(22,481)	(18,326)
Operating Segment Assets
Investments and other assets	15,788,380						15,788,380		14,607,822
DAC and VOBA	1,467,866						1,467,866		1,499,386
Other Intangible Assets, Net	247,958						247,958		262,181
Goodwill	215,254						215,254		215,254
Total assets	17,719,458						17,719,458		16,584,643
Acquisitions
Summarized financial information for the company's segments
Revenues	859,524			581,054			2,136,497	1,469,787
Pre-tax Adjusted Operating Income (Loss)	103,210			93,648			247,932	208,206
Operating Segment Assets
Investments and other assets	52,877,466						52,877,466		31,859,520
DAC and VOBA	885,600						885,600		458,977
Other Intangible Assets, Net	37,287						37,287		31,975
Goodwill	23,862						23,862		23,862
Total assets	53,824,215						53,824,215		32,374,334
Annuities
Summarized financial information for the company's segments
Revenues	210,114			110,386			542,736	321,880
Pre-tax Adjusted Operating Income (Loss)	27,684			36,249			109,886	112,234
Operating Segment Assets
Investments and other assets	21,092,340						21,092,340		20,160,279
DAC and VOBA	895,121						895,121		889,697
Other Intangible Assets, Net	161,509						161,509		156,785
Goodwill	343,247						343,247		343,247
Total assets	22,492,217						22,492,217		21,550,008
Stable Value Products
Summarized financial information for the company's segments
Revenues	59,954			59,328			187,118	158,944
Pre-tax Adjusted Operating Income (Loss)	20,863			27,126			71,208	76,198
Operating Segment Assets
Investments and other assets	5,324,149						5,324,149		5,107,334
DAC and VOBA	6,019						6,019		6,121
Other Intangible Assets, Net	6,889						6,889		7,389
Goodwill	113,924						113,924		113,924
Total assets	5,450,981						5,450,981		5,234,768
Asset Protection
Summarized financial information for the company's segments
Revenues	88,696			90,926			266,345	266,747
Pre-tax Adjusted Operating Income (Loss)	9,637			7,051			26,945	16,991
Operating Segment Assets
Investments and other assets	866,349						866,349		827,416
DAC and VOBA	172,984						172,984		172,149
Other Intangible Assets, Net	114,703						114,703		122,590
Goodwill	129,224						129,224		129,224
Total assets	1,283,260						1,283,260		1,251,379
Corporate and Other
Summarized financial information for the company's segments
Revenues	22,597			20,561			90,083	90,686
Pre-tax Adjusted Operating Income (Loss)	(36,563)			$ (41,927)			(119,675)	$ (119,474)
Operating Segment Assets
Investments and other assets	17,928,512						17,928,512		12,356,003
DAC and VOBA	0						0		0
Other Intangible Assets, Net	27,473						27,473		31,934
Goodwill	0						0		0
Total assets	$ 17,955,985						$ 17,955,985		$ 12,387,937