Schedule II - Condensed Financial Information of Registrant (Condensed Statements of Operations) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Revenues:
Net investment income	$ 403,849	$ 386,931	$ 370,882	$ 370,005	$ 363,947	$ 354,147	$ 336,143	$ 329,690	$ 1,531,667	$ 1,383,927	$ 1,286,923
Change in fair value of derivatives	146,231	39,218	270,883	48,493	444,985	193,028	64,040	373,962	504,825	1,076,015	221,138
Loss on extinguishment of debt									(12,502)	(32,515)	0
Total revenues	592,335	460,396	670,737	445,505	837,294	580,263	447,570	745,565	2,168,973	2,610,692	1,652,356
Expenses:
Change in fair value of embedded derivatives									32,321	133,968	286,899
Interest expense on notes payable									36,370	38,870	28,479
Interest expense on subordinated debentures issued to subsidiary trusts									12,122	12,088	13,458
Other operating costs and expenses									81,584	91,915	95,495
Total benefits and expenses									1,972,909	2,221,360	1,566,367
Income tax expense (benefit)									70,041	136,049	28,191
Net income	31,217	67,815	36,744	(9,753)	50,958	56,181	120,113	26,031	126,023	253,283	57,798
Parent Company [Member]
Revenues:
Net investment income									130	130	565
Dividends from subsidiary trusts									360	361	403
Investment advisory fees									58,044	44,469	36,178
Surplus note interest from subsidiary									4,080	4,080	4,080
Change in fair value of derivatives									(17,122)	144,012	(7,472)
Loss on extinguishment of debt									(12,502)	(32,515)	0
Total revenues									32,990	160,537	33,754
Expenses:
Change in fair value of embedded derivatives									(15,227)	141,974	(2,488)
Interest expense on notes payable									36,370	38,870	28,479
Interest expense on subordinated debentures issued to subsidiary trusts									12,122	12,088	13,458
Other operating costs and expenses									7,928	8,163	8,228
Total benefits and expenses									41,193	201,095	47,677
Loss before income taxes and equity in undistributed income of subsidiaries									(8,203)	(40,558)	(13,923)
Income tax expense (benefit)									664	(13,880)	(5,944)
Loss before equity in undistributed income of subsidiaries									(8,867)	(26,678)	(7,979)
Equity in undistributed income of subsidiaries									134,890	279,961	65,777
Net income									$ 126,023	$ 253,283	$ 57,798