OPERATING SEGMENTS (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Summarized financial information for the company's segments
Revenues	$ 1,169,644	$ 1,063,463	$ 2,233,155	$ 2,110,819
Pre-tax Adjusted Operating Income (Loss)	84,883	120,624	150,035	229,917
Realized (losses) gains on investments and derivatives	(23,989)	12,662	(67,205)	(9,987)
Income before income tax	60,894	133,286	82,830	219,930
Income tax expense	(8,626)	(43,654)	(12,287)	(71,959)
Net income	52,268	89,632	70,543	147,971
Adjusted operating income tax (expense) benefit	(13,664)	(39,222)	(26,400)	(75,454)
After-tax adjusted operating income	71,219	81,402	123,635	154,463
Income tax benefit (expense) on adjustments	5,038	(4,432)	14,113	3,495
Realized investment (losses) gains:
Derivative financial instruments	17,060	(63,794)	63,886	(124,694)
All other investments	(49,643)	53,535	(137,194)	76,376
Net impairment losses recognized in earnings	(5)	(2,785)	(3,650)	(7,986)
Less: related amortization	1,763	(15,703)	10,919	(26,447)
Less: VA GLWB economic cost	(10,362)	(10,003)	(20,672)	(19,870)
Operating Segment Assets
Investments and other assets	86,175,206		86,175,206		$ 75,451,948
DAC and VOBA	2,875,743		2,875,743		2,205,401
Other intangibles	638,922		638,922		662,916
Goodwill	793,470		793,470		793,470
Total assets	90,483,341		90,483,341		79,113,735
Life Marketing
Summarized financial information for the company's segments
Revenues	383,484	379,880	787,366	776,952
Pre-tax Adjusted Operating Income (Loss)	(6,805)	24,342	(21,973)	44,419
Operating Segment Assets
Investments and other assets	14,667,187		14,667,187		14,917,752
DAC and VOBA	1,421,313		1,421,313		1,320,776
Other intangibles	271,976		271,976		281,705
Goodwill	200,274		200,274		200,274
Total assets	16,560,750		16,560,750		16,720,507
Acquisitions
Summarized financial information for the company's segments
Revenues	509,639	387,464	888,733	788,831
Pre-tax Adjusted Operating Income (Loss)	59,038	68,278	114,558	121,945
Operating Segment Assets
Investments and other assets	32,435,800		32,435,800		19,588,133
DAC and VOBA	437,538		437,538		74,862
Other intangibles	33,267		33,267		34,548
Goodwill	14,524		14,524		14,524
Total assets	32,921,129		32,921,129		19,712,067
Annuities
Summarized financial information for the company's segments
Revenues	125,699	136,863	211,494	246,719
Pre-tax Adjusted Operating Income (Loss)	45,817	36,288	75,985	78,349
Operating Segment Assets
Investments and other assets	20,721,319		20,721,319		20,774,566
DAC and VOBA	840,715		840,715		772,634
Other intangibles	163,451		163,451		170,117
Goodwill	336,677		336,677		336,677
Total assets	22,062,162		22,062,162		22,053,994
Stable Value Products
Summarized financial information for the company's segments
Revenues	45,748	42,087	99,616	82,930
Pre-tax Adjusted Operating Income (Loss)	19,992	22,367	49,072	46,266
Operating Segment Assets
Investments and other assets	4,897,132		4,897,132		4,569,639
DAC and VOBA	7,284		7,284		6,864
Other intangibles	7,722		7,722		8,056
Goodwill	113,813		113,813		113,813
Total assets	5,025,951		5,025,951		4,698,372
Asset Protection
Summarized financial information for the company's segments
Revenues	88,130	93,290	175,821	183,634
Pre-tax Adjusted Operating Income (Loss)	5,641	4,674	9,940	8,624
Operating Segment Assets
Investments and other assets	818,643		818,643		708,605
DAC and VOBA	168,893		168,893		30,265
Other intangibles	127,912		127,912		133,234
Goodwill	128,182		128,182		128,182
Total assets	1,243,630		1,243,630		1,000,286
Corporate and Other
Summarized financial information for the company's segments
Revenues	16,944	23,879	70,125	31,753
Pre-tax Adjusted Operating Income (Loss)	(38,800)	$ (35,325)	(77,547)	$ (69,686)
Operating Segment Assets
Investments and other assets	12,635,125		12,635,125		14,893,253
DAC and VOBA	0		0		0
Other intangibles	34,594		34,594		35,256
Goodwill	0		0		0
Total assets	$ 12,669,719		$ 12,669,719		$ 14,928,509