Fair Value - Level 3 rollforward (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015		Dec. 31, 2014
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year		$ 769,384		$ 712,306
Realized and unrealized investment gains (losses) included in net income		3,230		15,992
Purchases		538,137		288,726
Settlements		(543,496)	[1]	(247,640)	[2]
Net transfers into/ (out of) Level 3		0		0
Balance, end of year		767,255		769,384
Change in unrealized investment gains (losses) relating to assets held at the end of year		9,630		17,972
Fixed maturities
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year		599,646		554,957
Realized and unrealized investment gains (losses) included in net income		5,452		20,491
Purchases		187,689		224,410
Settlements		(284,241)	[1]	(200,212)	[2]
Net transfers into/ (out of) Level 3		0		0
Balance, end of year		508,546		599,646
Change in unrealized investment gains (losses) relating to assets held at the end of year		6,282		20,931
Fixed maturities | U.S. states, territories and municipalities
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year		149,728		108,380
Realized and unrealized investment gains (losses) included in net income		16,660		12,322
Purchases		16,440		31,470
Settlements		(43,981)	[1]	(2,444)	[2]
Net transfers into/ (out of) Level 3		0		0
Balance, end of year		138,847		149,728
Change in unrealized investment gains (losses) relating to assets held at the end of year		16,650		12,315
Fixed maturities | Asset-backed securities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year		449,918		446,577
Realized and unrealized investment gains (losses) included in net income		(11,208)		8,169
Purchases		171,249		192,940
Settlements		(240,260)	[1]	(197,768)	[2]
Net transfers into/ (out of) Level 3		0		0
Balance, end of year		369,699		449,918
Change in unrealized investment gains (losses) relating to assets held at the end of year		(10,368)		8,616
Equities
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year		40,134		38,045
Realized and unrealized investment gains (losses) included in net income		2,008		2,089
Purchases		249,340		8
Settlements		(253,926)	[1]	(8)	[2]
Net transfers into/ (out of) Level 3		0		0
Balance, end of year		37,556		40,134
Change in unrealized investment gains (losses) relating to assets held at the end of year		528		2,089
Equities | Finance [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year		20,353		20,207
Realized and unrealized investment gains (losses) included in net income		2,540		146
Purchases		0		0
Settlements		(133)	[1]	0	[2]
Net transfers into/ (out of) Level 3		0		0
Balance, end of year		22,760		20,353
Change in unrealized investment gains (losses) relating to assets held at the end of year		2,540		146
Equities | Technology [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year		8,555		7,752
Realized and unrealized investment gains (losses) included in net income		(348)		803
Purchases		0		0
Settlements		0	[1]	0	[2]
Net transfers into/ (out of) Level 3		0		0
Balance, end of year		8,207		8,555
Change in unrealized investment gains (losses) relating to assets held at the end of year		(348)		803
Equities | Communications [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year		2,640		2,199
Realized and unrealized investment gains (losses) included in net income		(655)		441
Purchases		0		0
Settlements		0	[1]	0	[2]
Net transfers into/ (out of) Level 3		0		0
Balance, end of year		1,985		2,640
Change in unrealized investment gains (losses) relating to assets held at the end of year		(655)		441
Equities | Other equities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year		0		0
Realized and unrealized investment gains (losses) included in net income				0
Purchases				8
Settlements	[2]			(8)
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		8,586		7,887
Realized and unrealized investment gains (losses) included in net income		471		699
Purchases		249,340		0
Settlements		(253,793)	[1]	0	[2]
Sales	[1]	4,400
Net transfers into/ (out of) Level 3		0		0
Balance, end of year		4,604		8,586
Change in unrealized investment gains (losses) relating to assets held at the end of year		(1,009)		699
Other invested assets [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year		116,074		103,853
Realized and unrealized investment gains (losses) included in net income		(1,046)		(4,487)
Purchases		101,108		63,527
Settlements		(5,129)	[1]	(46,819)	[2]
Net transfers into/ (out of) Level 3		0		0
Balance, end of year		211,007		116,074
Change in unrealized investment gains (losses) relating to assets held at the end of year		6,072		(2,959)
Other invested assets [Member] | Derivatives, net [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year		(1,858)		(788)
Realized and unrealized investment gains (losses) included in net income		804		(759)
Purchases		(2,051)	[3]	(871)	[4]
Issuances		2,100		900
Settlements		8,456	[1]	560	[2]
Net transfers into/ (out of) Level 3		0		0
Balance, end of year		5,351		(1,858)
Change in unrealized investment gains (losses) relating to assets held at the end of year		7,648		(759)
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		44,817		41,446
Realized and unrealized investment gains (losses) included in net income		(2,223)		(372)
Purchases		88,675		35,988
Settlements		(5,347)	[1]	(32,245)	[2]
Net transfers into/ (out of) Level 3		0		0
Balance, end of year		125,922		44,817
Change in unrealized investment gains (losses) relating to assets held at the end of year		(2,223)		1,147
Other invested assets [Member] | Annuities and residuals [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year		13,243		24,064
Realized and unrealized investment gains (losses) included in net income		(866)		(207)
Purchases		0		0
Settlements		(3,941)	[1]	(10,614)	[2]
Net transfers into/ (out of) Level 3		0		0
Balance, end of year		8,436		13,243
Change in unrealized investment gains (losses) relating to assets held at the end of year		(472)		(167)
Other invested assets [Member] | Private equities [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year		59,872		39,131
Realized and unrealized investment gains (losses) included in net income		1,239		(3,149)
Purchases		14,484		28,410
Settlements		(4,297)	[1]	(4,520)	[2]
Sales	[1]	200
Net transfers into/ (out of) Level 3		0		0
Balance, end of year		71,298		59,872
Change in unrealized investment gains (losses) relating to assets held at the end of year		1,119		(3,180)
Funds Held - Directly Managed [Member]
Fair Value Assets Measured On Recurring Basis Unobservable Input Reconciliation [Line Items]
Balance, beginning of year		13,530		15,451
Realized and unrealized investment gains (losses) included in net income		(3,184)		(2,101)
Purchases		0		781
Settlements		(200)	[1]	(601)	[2]
Net transfers into/ (out of) Level 3		0		0
Balance, end of year		10,146		13,530
Change in unrealized investment gains (losses) relating to assets held at the end of year		(3,252)		(2,089)
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		13,398		15,165
Realized and unrealized investment gains (losses) included in net income		(3,252)		(2,102)
Purchases		0		781
Settlements		0	[1]	(446)	[2]
Net transfers into/ (out of) Level 3		0		0
Balance, end of year		10,146		13,398
Change in unrealized investment gains (losses) relating to assets held at the end of year		(3,252)		(2,102)
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		132		286
Realized and unrealized investment gains (losses) included in net income		68		1
Purchases		0		0
Settlements		(200)	[1]	(155)	[2]
Net transfers into/ (out of) Level 3		0		0
Balance, end of year		0		132
Change in unrealized investment gains (losses) relating to assets held at the end of year		$ 0		$ 13

[1] Settlements and sales of mutual funds and exchange traded funds and private equities include sales of $4.4 million and $0.2 million, respectively.

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

[3] Purchases and issuances of derivatives include issuances of $2.1 million.

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