Fair Value - Level 3 rollforward (Details) (USD $)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year	$ 712,306,000		$ 790,421,000
Realized and unrealized investment gains (losses) included in net income	15,992,000		(17,337,000)
Purchases	288,726,000		472,315,000
Settlements	(247,640,000)	[1]	(533,093,000)
Net transfers into/ (out of) Level 3	0		0
Balance, end of year	769,384,000		712,306,000
Change in unrealized investment gains (losses) relating to assets held at the end of year	17,972,000		(10,170,000)
Fixed maturities
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year	554,957,000		657,273,000
Realized and unrealized investment gains (losses) included in net income	20,491,000		(8,050,000)
Purchases	224,410,000		405,337,000
Settlements	(200,212,000)	[1]	(499,603,000)
Net transfers into/ (out of) Level 3	0		0
Balance, end of year	599,646,000		554,957,000
Change in unrealized investment gains (losses) relating to assets held at the end of year	20,931,000		(7,784,000)
Fixed maturities | U.S. states, territories and municipalities
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year	108,380,000		233,235,000
Realized and unrealized investment gains (losses) included in net income	12,322,000		(4,440,000)
Purchases	31,470,000		103,860,000
Settlements	(2,444,000)	[1]	(224,275,000)
Net transfers into/ (out of) Level 3	0		0
Balance, end of year	149,728,000		108,380,000
Sales			(223,700,000)
Change in unrealized investment gains (losses) relating to assets held at the end of year	12,315,000		1,234,000
Fixed maturities | Corporate
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year			100,904,000
Realized and unrealized investment gains (losses) included in net income			(2,271,000)
Purchases			0
Settlements			(98,633,000)
Net transfers into/ (out of) Level 3			0
Balance, end of year			0
Change in unrealized investment gains (losses) relating to assets held at the end of year			0
Fixed maturities | Asset-backed securities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year	446,577,000		323,134,000
Realized and unrealized investment gains (losses) included in net income	8,169,000		(1,339,000)
Purchases	192,940,000		301,477,000
Settlements	(197,768,000)	[1]	(176,695,000)	[2]
Net transfers into/ (out of) Level 3	0		0
Balance, end of year	449,918,000		446,577,000
Sales			(13,700,000)
Change in unrealized investment gains (losses) relating to assets held at the end of year	8,616,000		(9,018,000)
Equities
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year	38,045,000		27,728,000
Realized and unrealized investment gains (losses) included in net income	2,089,000		3,277,000
Purchases	8,000		7,040,000
Settlements	(8,000)	[1]	0
Net transfers into/ (out of) Level 3	0		0
Balance, end of year	40,134,000		38,045,000
Change in unrealized investment gains (losses) relating to assets held at the end of year	2,089,000		3,277,000
Equities | Finance [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year	20,207,000		13,477,000
Realized and unrealized investment gains (losses) included in net income	146,000		1,730,000
Purchases	0		5,000,000
Settlements	0	[1]	0
Net transfers into/ (out of) Level 3	0		0
Balance, end of year	20,353,000		20,207,000
Change in unrealized investment gains (losses) relating to assets held at the end of year	146,000		1,730,000
Equities | Technology [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year	7,752,000		6,987,000
Realized and unrealized investment gains (losses) included in net income	803,000		765,000
Purchases	0		0
Settlements	0	[1]	0
Net transfers into/ (out of) Level 3	0		0
Balance, end of year	8,555,000		7,752,000
Change in unrealized investment gains (losses) relating to assets held at the end of year	803,000		765,000
Equities | Communications [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year	2,199,000		0
Realized and unrealized investment gains (losses) included in net income	441,000		159,000
Purchases	0		2,040,000
Settlements	0	[1]	0
Net transfers into/ (out of) Level 3	0		0
Balance, end of year	2,640,000		2,199,000
Change in unrealized investment gains (losses) relating to assets held at the end of year	441,000		159,000
Equities | Other equities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year	0
Realized and unrealized investment gains (losses) included in net income	0
Purchases	8,000
Settlements	(8,000)	[1]
Net transfers into/ (out of) Level 3	0
Balance, end of year	0
Change in unrealized investment gains (losses) relating to assets held at the end of year	0
Equities | Mutual funds and exchange traded funds [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year	7,887,000		7,264,000
Realized and unrealized investment gains (losses) included in net income	699,000		623,000
Purchases	0		0
Settlements	0	[1]	0
Net transfers into/ (out of) Level 3	0		0
Balance, end of year	8,586,000		7,887,000
Change in unrealized investment gains (losses) relating to assets held at the end of year	699,000		623,000
Other invested assets [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year	103,853,000		87,099,000
Realized and unrealized investment gains (losses) included in net income	(4,487,000)		(10,451,000)
Purchases	63,527,000		59,938,000
Settlements	(46,819,000)	[1]	(32,733,000)
Net transfers into/ (out of) Level 3	0		0
Balance, end of year	116,074,000		103,853,000
Change in unrealized investment gains (losses) relating to assets held at the end of year	(2,959,000)		(4,614,000)
Other invested assets [Member] | Derivatives, net [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year	(788,000)		3,911,000
Realized and unrealized investment gains (losses) included in net income	(759,000)		(6,136,000)
Purchases	(871,000)	[3]	121,000	[4]
Settlements	560,000	[1]	1,316,000	[2]
Net transfers into/ (out of) Level 3	0		0
Balance, end of year	(1,858,000)		(788,000)
Issuances	900,000		800,000
Sales			(1,200,000)
Change in unrealized investment gains (losses) relating to assets held at the end of year	(759,000)		(69,000)
Other invested assets [Member] | Notes And Loan Receivables And Notes Securitization [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year	41,446,000		34,902,000
Realized and unrealized investment gains (losses) included in net income	(372,000)		936,000
Purchases	35,988,000		15,732,000
Settlements	(32,245,000)	[1]	(10,124,000)
Net transfers into/ (out of) Level 3	0		0
Balance, end of year	44,817,000		41,446,000
Change in unrealized investment gains (losses) relating to assets held at the end of year	1,147,000		936,000
Other invested assets [Member] | Annuities and residuals [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year	24,064,000		46,882,000
Realized and unrealized investment gains (losses) included in net income	(207,000)		1,107,000
Purchases	0		0
Settlements	(10,614,000)	[1]	(23,925,000)	[2]
Net transfers into/ (out of) Level 3	0		0
Balance, end of year	13,243,000		24,064,000
Sales			(6,300,000)
Change in unrealized investment gains (losses) relating to assets held at the end of year	(167,000)		877,000
Other invested assets [Member] | Private equities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year	39,131,000		1,404,000
Realized and unrealized investment gains (losses) included in net income	(3,149,000)		(6,358,000)
Purchases	28,410,000		44,085,000
Settlements	(4,520,000)	[1]	0
Net transfers into/ (out of) Level 3	0		0
Balance, end of year	59,872,000		39,131,000
Change in unrealized investment gains (losses) relating to assets held at the end of year	(3,180,000)		(6,358,000)
Funds Held - Directly Managed [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year	15,451,000		18,321,000
Realized and unrealized investment gains (losses) included in net income	(2,101,000)		(2,113,000)
Purchases	781,000		0
Settlements	(601,000)	[1]	(757,000)
Net transfers into/ (out of) Level 3	0		0
Balance, end of year	13,530,000		15,451,000
Change in unrealized investment gains (losses) relating to assets held at the end of year	(2,089,000)		(1,049,000)
Funds Held - Directly Managed [Member] | Other invested assets funds held directly managed [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year	15,165,000		17,976,000
Realized and unrealized investment gains (losses) included in net income	(2,102,000)		(2,054,000)
Purchases	781,000		0
Settlements	(446,000)	[1]	(757,000)
Net transfers into/ (out of) Level 3	0		0
Balance, end of year	13,398,000		15,165,000
Change in unrealized investment gains (losses) relating to assets held at the end of year	(2,102,000)		(990,000)
Funds Held - Directly Managed [Member] | U.S. states, territories and municipalities
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year	286,000		345,000
Realized and unrealized investment gains (losses) included in net income	1,000		(59,000)
Purchases	0		0
Settlements	(155,000)	[1]	0
Net transfers into/ (out of) Level 3	0		0
Balance, end of year	132,000		286,000
Change in unrealized investment gains (losses) relating to assets held at the end of year	$ 13,000		$ (59,000)

[1] (2)There were no sales for the year ended December 31, 2014.

[2] Settlements and sales of U.S. states, territories and municipalities, asset-backed securities, derivatives and annuities and residuals include sales of $223.7 million, $13.7 million, $1.2 million and $6.3 million, respectively

[3] Purchases and issuances of derivatives include issuances of $0.9 million.

[4] Purchases and issuances of derivatives include issuances of $0.8 million.