Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Investment portfolio:
Fixed maturity securities, available-for-sale, at fair value (amortized cost of $9,618,789 and $9,638,404)	$ 10,207,514	$ 10,141,850
Short term investments, at fair value	919,784	734,046
Other invested assets	194,447	222,869
Total investment portfolio	11,321,745	11,098,765
Cash	175,347	214,544
Premiums receivable, net of ceding commissions payable	964,063	1,002,852
Ceded unearned premium reserve	590,781	708,872
Deferred acquisition costs	126,755	132,418
Reinsurance recoverable on unpaid losses	(170,495)	(69,300)
Salvage and subrogation recoverable	376,760	367,718
Credit derivative assets	429,891	468,933
Deferred tax asset, net	815,084	803,529
Current income tax receivable	63,192	76,430
Financial guaranty variable interest entities' assets, at fair value	2,725,979	2,819,077
Other assets	314,372	262,222
Total assets	18,074,464	18,024,660
Liabilities and shareholders' equity
Unearned premium reserve	5,583,380	5,962,799
Loss and loss adjustment expense reserve	995,217	679,011
Reinsurance balances payable, net	186,676	170,982
Long-term debt	846,354	1,038,302
Credit derivative liabilities	2,095,852	1,772,803
Financial guaranty variable interest entities' liabilities with recourse, at fair value	2,239,067	2,396,945
Financial guaranty variable interest entities' liabilities without recourse, at fair value	1,042,275	1,061,497
Other liabilities	361,577	290,756
Total liabilities	13,350,398	13,373,095
Commitments and contingencies (See Note 12)
Common stock ($0.01 par value, 500,000,000 shares authorized; 193,956,481 and 182,235,798 shares issued and outstanding in 2012 and 2011)	1,939	1,822
Additional paid-in capital	2,719,988	2,569,922
Retained earnings	1,568,397	1,707,922
Accumulated other comprehensive income, net of tax of $159,679 and $135,344	429,342	367,499
Deferred equity compensation (320,193 shares in 2012 and 2011)	4,400	4,400
Total shareholders' equity	4,724,066	4,651,565
Total liabilities and shareholders' equity	$ 18,074,464	$ 18,024,660