Fair Value (Details - Level 3 inputs and transfers) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	$ 571,579,000	$ 300,462,000	$ 500,286,000	$ 291,769,000
Realized and unrealized investment gains (losses) included in net income	9,368,000	3,423,000	(34,172,000)	(4,886,000)
Purchases	78,480,000		182,968,000
Sales	(110,187,000)		(140,022,000)
Net purchases, sales and settlements		65,559,000		75,642,000
Net transfers (out of)/ into Level 3	0	0	40,180,000	6,919,000
Balance, end of period	549,240,000	369,444,000	549,240,000	369,444,000
Change in unrealized investment gains (losses) relating to assets held at the end of period	(3,019,000)	3,423,000	(3,603,000)	(6,825,000)
Fair value of financial instrument liabilities [Line Items]
Debt related to senior notes	750,000,000		750,000,000		750,000,000
Debt related to capital efficient notes	70,989,000		70,989,000		70,989,000
Fixed maturities [Member] | Funds held directly managed [Member]
Fair Value - Other Details [Line Items]
Transfers into Level 3				16,900,000
Fixed maturities [Member] | Trading securities [Member]
Fair Value - Other Details [Line Items]
Transfers out of Level 3				18,100,000
Transfers into Level 3			40,200,000
US Government and agencies [Member] | Fixed maturities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	55,929,000	9,720,000	55,124,000	4,286,000
Realized and unrealized investment gains (losses) included in net income	819,000	272,000	1,624,000	272,000
Purchases	30,064,000		30,064,000
Sales	(30,000)		(30,000)
Net purchases, sales and settlements		7,000		9,727,000
Net transfers (out of)/ into Level 3	0	0	0	(4,286,000)
Balance, end of period	86,782,000	9,999,000	86,782,000	9,999,000
Change in unrealized investment gains (losses) relating to assets held at the end of period	819,000	272,000	1,624,000	272,000
Corporate [Member] | Fixed maturities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	115,107,000	10,057,000	76,982,000	15,041,000
Realized and unrealized investment gains (losses) included in net income	2,049,000	300,000	(37,066,000)	423,000
Purchases	84,000		40,878,000
Sales	(812,000)		(4,546,000)
Net purchases, sales and settlements		5,080,000		10,900,000
Net transfers (out of)/ into Level 3	0	0	40,180,000	(10,927,000)
Balance, end of period	116,428,000	15,437,000	116,428,000	15,437,000
Change in unrealized investment gains (losses) relating to assets held at the end of period	2,049,000	300,000	2,368,000	423,000
Asset-backed securities [Member] | Fixed maturities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	262,408,000	84,984,000	213,139,000	99,952,000
Realized and unrealized investment gains (losses) included in net income	7,707,000	7,359,000	10,678,000	4,601,000
Purchases	47,130,000		101,644,000
Sales	(55,402,000)		(63,618,000)
Net purchases, sales and settlements		133,615,000		124,305,000
Net transfers (out of)/ into Level 3	0	0	0	(2,900,000)
Balance, end of period	261,843,000	225,958,000	261,843,000	225,958,000
Change in unrealized investment gains (losses) relating to assets held at the end of period	(2,660,000)	7,359,000	4,257,000	4,576,000
Residential mortgage-backed securities [Member] | Fixed maturities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	4,301,000	95,029,000	0	77,440,000
Realized and unrealized investment gains (losses) included in net income	846,000	0	1,385,000	191,000
Purchases	0		4,212,000
Sales	(5,147,000)		(5,597,000)
Net purchases, sales and settlements		(95,029,000)		(77,631,000)
Net transfers (out of)/ into Level 3	0	0	0	0
Balance, end of period	0	0	0	0
Change in unrealized investment gains (losses) relating to assets held at the end of period	0	0	0	0
Other mortgage-backed securities [Member] | Fixed maturities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	576,000	811,000	290,000	874,000
Realized and unrealized investment gains (losses) included in net income	(191,000)	123,000	(224,000)	153,000
Purchases	0		408,000
Sales	(384,000)		(473,000)
Net purchases, sales and settlements		(80,000)		(173,000)
Net transfers (out of)/ into Level 3	0	0	0	0
Balance, end of period	1,000	854,000	1,000	854,000
Change in unrealized investment gains (losses) relating to assets held at the end of period	(166,000)	123,000	(203,000)	153,000
Fixed maturities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	438,321,000	200,601,000	345,535,000	197,593,000
Realized and unrealized investment gains (losses) included in net income	11,230,000	8,054,000	(23,603,000)	5,640,000
Purchases	77,278,000		177,206,000
Sales	(61,775,000)		(74,264,000)
Net purchases, sales and settlements		43,593,000		67,128,000
Net transfers (out of)/ into Level 3	0	0	40,180,000	(18,113,000)
Balance, end of period	465,054,000	252,248,000	465,054,000	252,248,000
Change in unrealized investment gains (losses) relating to assets held at the end of period	42,000	8,054,000	8,046,000	5,424,000
Finance [Member] | Equity securities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	161,000	2,459,000	2,486,000	2,488,000
Realized and unrealized investment gains (losses) included in net income	2,000	(1,039,000)	239,000	(1,068,000)
Purchases	0		0
Sales	0		(2,562,000)
Net purchases, sales and settlements		695,000		695,000
Net transfers (out of)/ into Level 3	0	0	0	0
Balance, end of period	163,000	2,115,000	163,000	2,115,000
Change in unrealized investment gains (losses) relating to assets held at the end of period	2,000	(1,039,000)	13,000	(1,068,000)
Industrials [Member] | Equity securities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period				805,000
Realized and unrealized investment gains (losses) included in net income				(84,000)
Net purchases, sales and settlements				(721,000)
Net transfers (out of)/ into Level 3				0
Balance, end of period		0		0
Change in unrealized investment gains (losses) relating to assets held at the end of period				0
Mutual funds and exchange traded funds [Member] | Equity securities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	41,451,000	35,670,000	40,927,000	34,810,000
Realized and unrealized investment gains (losses) included in net income	594,000	(1,058,000)	1,242,000	(198,000)
Purchases	0		0
Sales	(35,503,000)		(35,627,000)
Net purchases, sales and settlements		5,000,000		5,000,000
Net transfers (out of)/ into Level 3	0	0	0	0
Balance, end of period	6,542,000	39,612,000	6,542,000	39,612,000
Change in unrealized investment gains (losses) relating to assets held at the end of period	(804,000)	(1,058,000)	(382,000)	(198,000)
Equity securities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	41,612,000	38,129,000	43,413,000	38,103,000
Realized and unrealized investment gains (losses) included in net income	596,000	(2,097,000)	1,481,000	(1,350,000)
Purchases	0		0
Sales	(35,503,000)		(38,189,000)
Net purchases, sales and settlements		5,695,000		4,974,000
Net transfers (out of)/ into Level 3	0	0	0	0
Balance, end of period	6,705,000	41,727,000	6,705,000	41,727,000
Change in unrealized investment gains (losses) relating to assets held at the end of period	(802,000)	(2,097,000)	(369,000)	(1,266,000)
Other invested assets other assets [Member ] | Other invested assets [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	84,662,000	25,918,000	86,278,000	25,815,000
Realized and unrealized investment gains (losses) included in net income	(1,303,000)	(253,000)	(3,207,000)	(169,000)
Purchases	3,568,000		6,548,000
Sales	(12,909,000)		(15,601,000)
Net purchases, sales and settlements		24,624,000		24,643,000
Net transfers (out of)/ into Level 3	0	0	0	0
Balance, end of period	74,018,000	50,289,000	74,018,000	50,289,000
Change in unrealized investment gains (losses) relating to assets held at the end of period	(1,016,000)	(253,000)	(2,497,000)	(169,000)
Other invested assets [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	67,620,000	17,920,000	78,324,000	16,454,000
Realized and unrealized investment gains (losses) included in net income	(981,000)	1,519,000	(12,010,000)	4,146,000
Purchases	(1,247,000)		1,770,000
Sales	(12,909,000)		(15,601,000)
Net purchases, sales and settlements		16,271,000		6,944,000
Net transfers (out of)/ into Level 3	0	0	0	8,166,000
Balance, end of period	52,483,000	35,710,000	52,483,000	35,710,000
Change in unrealized investment gains (losses) relating to assets held at the end of period	(782,000)	1,519,000	(11,390,000)	2,321,000
Other invested assets [Member] | Derivatives, net [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	(17,042,000)	(7,998,000)	(7,954,000)	(9,361,000)
Realized and unrealized investment gains (losses) included in net income	322,000	1,772,000	(8,803,000)	4,315,000
Purchases	(4,815,000)		(4,778,000)
Sales	0		0
Net purchases, sales and settlements		(8,353,000)		(17,699,000)
Net transfers (out of)/ into Level 3	0	0	0	8,166,000
Balance, end of period	(21,535,000)	(14,579,000)	(21,535,000)	(14,579,000)
Change in unrealized investment gains (losses) relating to assets held at the end of period	234,000	1,772,000	(8,893,000)	2,490,000
US Government and agencies [Member] | Funds Held - Directly Managed investment [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	366,000	204,000	368,000	375,000
Realized and unrealized investment gains (losses) included in net income	(11,000)	153,000	(13,000)	(18,000)
Purchases	0		0
Sales	0		0
Net purchases, sales and settlements		0		0
Net transfers (out of)/ into Level 3	0	0	0	0
Balance, end of period	355,000	357,000	355,000	357,000
Change in unrealized investment gains (losses) relating to assets held at the end of period	(11,000)	153,000	(13,000)	(18,000)
Mortgage/asset-backed securities [Member] | Funds Held - Directly Managed investment [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period		13,260,000	12,118,000	142,000
Realized and unrealized investment gains (losses) included in net income		(683,000)	(150,000)	(4,431,000)
Purchases			0
Sales			(11,968,000)
Net purchases, sales and settlements		0		0
Net transfers (out of)/ into Level 3		0	0	16,866,000
Balance, end of period	0	12,577,000	0	12,577,000
Change in unrealized investment gains (losses) relating to assets held at the end of period		(683,000)	0	(4,426,000)
Other invested assets funds held directly managed [Member] | Funds Held - Directly Managed investment [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	22,456,000	30,348,000	20,528,000	35,685,000
Realized and unrealized investment gains (losses) included in net income	(736,000)	(3,523,000)	1,192,000	(8,860,000)
Purchases	0		0
Sales	0		0
Net purchases, sales and settlements		0		0
Net transfers (out of)/ into Level 3	0	0	0	0
Balance, end of period	21,720,000	26,825,000	21,720,000	26,825,000
Change in unrealized investment gains (losses) relating to assets held at the end of period	(736,000)	(3,523,000)	1,192,000	(8,860,000)
Funds Held - Directly Managed investment [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	22,822,000	43,812,000	33,014,000	39,619,000
Realized and unrealized investment gains (losses) included in net income	(747,000)	(4,053,000)	1,029,000	(13,322,000)
Purchases	0		0
Sales	0		(11,968,000)
Net purchases, sales and settlements		0		(3,404,000)
Net transfers (out of)/ into Level 3	0	0	0	16,866,000
Balance, end of period	22,075,000	39,759,000	22,075,000	39,759,000
Change in unrealized investment gains (losses) relating to assets held at the end of period	(747,000)	(4,053,000)	1,179,000	(13,304,000)
Funds Held - Directly Managed investment [Member] | Non US Sovereign Government Supranational And Government Related Debt Securities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period				3,417,000
Realized and unrealized investment gains (losses) included in net income				(13,000)
Net purchases, sales and settlements				(3,404,000)
Net transfers (out of)/ into Level 3				0
Balance, end of period		0		0
Change in unrealized investment gains (losses) relating to assets held at the end of period				0
Short-term investments [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of period	1,204,000		0
Realized and unrealized investment gains (losses) included in net income	(730,000)		(1,069,000)
Purchases	2,449,000		3,992,000
Sales	0		0
Net transfers (out of)/ into Level 3	0		0
Balance, end of period	2,923,000		2,923,000
Change in unrealized investment gains (losses) relating to assets held at the end of period	(730,000)		(1,069,000)
Trading securities [Member] | Derivatives, net [Member]
Fair Value - Other Details [Line Items]
Transfers out of Level 3				(8,200,000)
Estimate of Fair Value, Fair Value Disclosure [Member]
Fair value of financial instrument liabilities [Line Items]
Debt related to senior notes	793,773,000		793,773,000		781,950,000
Debt related to capital efficient notes	61,133,000		61,133,000		59,261,000
Carrying value [Member]
Fair value of financial instrument liabilities [Line Items]
Debt related to senior notes	750,000,000		750,000,000		750,000,000
Debt related to capital efficient notes	63,384,000		63,384,000		63,384,000
Funds held directly managed [Member]
Fair Value - Other Details [Line Items]
Cash and cash equivalents	149,300,000		149,300,000		129,200,000
Accrued investment income	14,900,000		14,900,000		19,900,000
Other net assets	56,500,000		56,500,000		80,100,000
Trading securities [Member]
Fair Value - Other Details [Line Items]
Aggregate carrying amount of other invested assets not carried at fair value	$ 297,600,000		$ 297,600,000		$ 241,000,000