Condensed Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Premiums written—insurance:
Direct	$ 232,086	$ 187,726	$ 650,188	$ 552,575
Assumed	(918)	(251)	(89,434)	(10,415)
Ceded	(21,891)	(9,188)	(91,867)	(28,346)
Net premiums written	209,277	178,287	468,887	513,814
Decrease in unearned premiums	(18,314)	1,368	76,220	57,798
Net premiums earned—insurance	190,963	179,655	545,107	571,612
Net investment income	25,635	38,763	91,225	124,826
Net gains on investments	84,659	81,640	178,537	163,311
Total other-than-temporary impairment ('OTTI') losses	0	(20)	0	(31)
Losses recognized in other comprehensive income (loss)	0	0	0	0
Net impairment losses recognized in earnings	0	(20)	0	(31)
Change in fair value of derivative instruments	(41,056)	126,008	(146,937)	558,626
Net (losses) gains on other financial instruments	(740)	80,602	(80,454)	160,900
Gain on sale of affiliate	0	0	7,708	0
Other income	1,328	1,404	4,163	4,048
Total revenues	260,789	508,052	599,349	1,583,292
Expenses:
Provision for losses	176,352	249,598	653,374	940,537
Change in reserve for premium deficiency	966	(1,942)	1,505	(6,427)
Policy acquisition costs	12,927	11,449	51,778	39,967
Other operating expenses	50,429	45,240	140,776	137,413
Interest expense	12,520	14,094	39,249	47,197
Total expenses	253,194	318,439	886,682	1,158,687
Equity in net (loss) income of affiliates	0	0	(13)	65
Pretax (loss) income	7,595	189,613	(287,346)	424,670
Income tax (benefit) provision	(6,730)	6,045	(13,180)	981
Net (loss) income	$ 14,325	$ 183,568	$ (274,166)	$ 423,689
Basic net (loss) income per share	$ 0.11	$ 1.39	$ (2.07)	$ 3.20
Diluted net (loss) income per share	$ 0.11	$ 1.37	$ (2.07)	$ 3.16
Weighted-average number of common shares outstanding—basic	132,521	132,364	132,530	132,366
Weighted-average number of common and common equivalent shares outstanding—diluted	134,033	133,513	132,530	133,867
Dividends per share	$ 0.0025	$ 0.0025	$ 0.0075	$ 0.0075