Condensed Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Premiums written—insurance:
Direct	$ 214,349	$ 174,008	$ 418,102	$ 364,849
Assumed	(1,028)	(11,788)	(88,516)	(10,164)
Ceded	(31,389)	(9,442)	(69,976)	(19,158)
Net premiums written	181,932	152,778	259,610	335,527
Decrease in unearned premiums	4,847	36,156	94,534	56,430
Net premiums earned—insurance	186,779	188,934	354,144	391,957
Net investment income	30,877	43,823	65,590	86,063
Net gains on investments	26,419	44,236	93,878	81,671
Total other-than-temporary impairment ('OTTI') losses	0	(11)	0	(11)
Losses recognized in other comprehensive income (loss)	0	0	0	0
Net impairment losses recognized in earnings	0	(11)	0	(11)
Change in fair value of derivative instruments	(33,124)	188,726	(105,881)	432,618
Net (losses) gains on other financial instruments	(61,862)	5,047	(79,714)	80,298
Gain on sale of affiliate	7,708	0	7,708	0
Other income	1,395	1,196	2,835	2,644
Total revenues	158,192	471,951	338,560	1,075,240
Expenses:
Provision for losses	210,868	263,566	477,022	690,939
Change in reserve for premium deficiency	559	(3,102)	539	(4,485)
Policy acquisition costs	10,805	14,387	38,851	28,518
Other operating expenses	40,193	45,954	90,347	92,173
Interest expense	12,581	16,079	26,729	33,103
Total expenses	275,006	336,884	633,488	840,248
Equity in net (loss) income of affiliates	(2)	0	(13)	65
Pretax (loss) income	(116,816)	135,067	(294,941)	235,057
Income tax (benefit) provision	2,443	(2,048)	(6,450)	(5,064)
Net (loss) income	$ (119,259)	$ 137,115	$ (288,491)	$ 240,121
Basic net (loss) income per share	$ (0.90)	$ 1.04	$ (2.18)	$ 1.82
Diluted net (loss) income per share	$ (0.90)	$ 1.03	$ (2.18)	$ 1.80
Weighted-average number of common shares outstanding—basic	132,346	132,185	132,350	132,185
Weighted-average number of common and common equivalent shares outstanding—diluted	132,346	133,614	132,350	133,724
Dividends per share	$ 0.0025	$ 0.0025	$ 0.0050	$ 0.0050