Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Changes in Level 3 Assets and Liabilities) (Details) - USD ($) $ in Thousands		3 Months Ended			9 Months Ended
		Sep. 30, 2017		Sep. 30, 2016	Sep. 30, 2017		Sep. 30, 2016
US Government Agencies Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, end of period		$ 23,251			$ 23,251
Foreign Government Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, end of period		5,628		$ 13,426	5,628		$ 13,426
Foreign Government Debt Securities [Member] | Other Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				0	0		0
Funds Withheld At Interest Embedded Derivatives [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		61,281		(91,981)	(22,529)		(76,698)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		0		0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	0		0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales				0			0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	0		0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3				0			0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0		0	0		0
Fair Value, end of period		84,325		(42,903)	84,325		(42,903)
Funds Withheld At Interest Embedded Derivatives [Member] | Investment Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				0			0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)				0			0
Funds Withheld At Interest Embedded Derivatives [Member] | Gain (Loss) on Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		23,044		49,078	106,854		33,795
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		23,044		49,078	106,854		33,795
Funds Withheld At Interest Embedded Derivatives [Member] | Interest Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0		0	0		0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0	0		0
Funds Withheld At Interest Embedded Derivatives [Member] | Other Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0		0	0		0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0	0		0
Longevity Swap [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		33,349		17,781	26,958		14,996
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		1,144		327	3,689		631
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0	[1]	0	0	[1]	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales				0			0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		0	[1]	0	0	[1]	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3				0			0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3				0	0		0
Fair Value, end of period		37,827		27,029	37,827		27,029
Longevity Swap [Member] | Investment Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				0			0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)				0			0
Longevity Swap [Member] | Gain (Loss) on Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0		0	0		0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0	0		0
Longevity Swap [Member] | Interest Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0		0	0		0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0	0		0
Longevity Swap [Member] | Other Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		3,334		8,921	7,180		11,402
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		3,334		8,921	7,180		11,402
Interest Sensitive Contract Liabilities Embedded Derivatives [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Sales				0			0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3				0			0
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		(974,631)		(1,125,380)	(990,308)		(1,070,584)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Other Comprehensive Income (Loss)		0		0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases	[1]	(18,736)		(11,853)	(51,276)		(9,817)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	[1]	21,809		19,225	63,047		54,096
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3		0		0	0		0
Fair Value, end of period		(989,940)		(1,130,124)	(989,940)		(1,130,124)
Interest Sensitive Contract Liabilities Embedded Derivatives [Member] | Investment Income [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings				0			0
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)				0			0
Interest Sensitive Contract Liabilities Embedded Derivatives [Member] | Gain (Loss) on Investments [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings		10,047		(7,988)	(9,005)		83,089
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)		11,900		(3,969)	(2,934)		92,842
Interest Sensitive Contract Liabilities Embedded Derivatives [Member] | Interest Income [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings		(8,335)		(20,104)	(20,408)		(20,730)
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)		30,145		39,329	83,456		74,826
Interest Sensitive Contract Liabilities Embedded Derivatives [Member] | Other Income [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings		0		0	0		0
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0	0		0
Mortality Swap [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Sales	[1]			0			0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3				0			0
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		(1,552)		(1,997)	(2,462)		(2,619)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Other Comprehensive Income (Loss)		1		0	1		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases	[1]	0		0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	[1]	0		329	1,700		329
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3		0		0	0		0
Fair Value, end of period		(1,683)		(2,068)	(1,683)		(2,068)
Mortality Swap [Member] | Investment Income [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings				0			0
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)				0			0
Mortality Swap [Member] | Gain (Loss) on Investments [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings		0		0	0		0
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0	0		0
Mortality Swap [Member] | Interest Income [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings		0		0	0		0
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0	0		0
Mortality Swap [Member] | Other Income [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings		(132)		(400)	(922)		222
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(132)		(400)	(922)		222
Short-term Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		3,548			3,346
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(3)			1
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	(3,164)			(3,520)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	(114)			(272)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		3,236			3,236
Fair Value, end of period		3,359			3,359
Short-term Investments [Member] | Gain (Loss) on Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0			0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0			0
Short-term Investments [Member] | Interest Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0			0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0			0
Short-term Investments [Member] | Other Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0			0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0			0
Available-for-sale Securities [Member] | Corporate Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		1,291,054		1,297,382	1,272,253		1,226,970
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(2,700)		(19,635)	(2,300)		36,438
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	(107,670)		(54,492)	(257,671)		(195,070)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]	(26,337)		(26,320)	(49,511)		(36,803)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	(88,551)		(44,110)	(234,552)		(141,065)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		3,844		0	35,042		10,206
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		(12,973)		23,255	12,973		28,987
Fair Value, end of period		1,272,020		1,255,904	1,272,020		1,255,904
Available-for-sale Securities [Member] | Corporate Debt Securities [Member] | Investment Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		(383)		(567)	(1,202)		(1,986)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(394)		(489)	(1,213)		(1,917)
Available-for-sale Securities [Member] | Corporate Debt Securities [Member] | Gain (Loss) on Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		396		17,917	7,592		(3,939)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)					(2,788)
Available-for-sale Securities [Member] | Corporate Debt Securities [Member] | Interest Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							0
Available-for-sale Securities [Member] | Canadian Provincial Governments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		533,270		554,192	475,965		416,076
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(11,365)		16,342	39,669		148,407
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	0		0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]	0		0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	0		0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0		0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0		0	0		0
Fair Value, end of period		525,365		573,619	525,365		573,619
Available-for-sale Securities [Member] | Canadian Provincial Governments [Member] | Investment Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		3,460		3,085	9,731		9,136
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		3,460		3,085	9,731		9,136
Available-for-sale Securities [Member] | Canadian Provincial Governments [Member] | Gain (Loss) on Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0		0	0		0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)					0
Available-for-sale Securities [Member] | Canadian Provincial Governments [Member] | Interest Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							0
Available-for-sale Securities [Member] | Residential mortgage-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		148,685		165,979	160,291		330,649
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		104		2,597	2,716		2,104
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	(26,765)		(27,548)	(72,582)		(99,776)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]	(3,553)		0	(18,624)		(167,684)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	(3,645)		(6,935)	(15,084)		(31,839)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		15		1,544	5,515		1,544
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		(50,390)		0	89,621		41,524
Fair Value, end of period		117,995		190,693	117,995		190,693
Available-for-sale Securities [Member] | Residential mortgage-backed securities | Investment Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		(30)		(40)	(304)		(411)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(27)		(40)	(155)		2
Available-for-sale Securities [Member] | Residential mortgage-backed securities | Gain (Loss) on Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		44		0	524		(1,922)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)					(346)
Available-for-sale Securities [Member] | Residential mortgage-backed securities | Interest Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							0
Available-for-sale Securities [Member] | Asset-backed securities
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		201,589		298,816	219,280		303,836
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(101)		3,410	6,802		(4,324)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	0		(5,013)	(45,215)		(102,063)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]	0		0	0		38,681
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	(15,243)		(18,602)	(60,966)		(26,523)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		36,994		28,285	75,752		53,081
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		(78,202)		93,444	142,575		167,501
Fair Value, end of period		145,197		223,651	145,197		223,651
Available-for-sale Securities [Member] | Asset-backed securities | Investment Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		160		173	1,689		599
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		156		173	556		523
Available-for-sale Securities [Member] | Asset-backed securities | Gain (Loss) on Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0		0	0		1,101
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)					0
Available-for-sale Securities [Member] | Asset-backed securities | Interest Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							0
Available-for-sale Securities [Member] | US States and Political Subdivisions Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		34,434		35,246	41,666		38,342
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(208)		553	(228)		1,725
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	0		(1,986)	0		(1,986)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]			0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	(35)		(32)	(309)		(290)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		7,295		0	7,295		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0		0	6,844		4,205
Fair Value, end of period		41,512		37,763	41,512		37,763
Available-for-sale Securities [Member] | US States and Political Subdivisions Debt Securities [Member] | Investment Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		26		10	(68)		205
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		26		10	(68)		205
Available-for-sale Securities [Member] | US States and Political Subdivisions Debt Securities [Member] | Gain (Loss) on Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				0	0		0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)				0			0
Available-for-sale Securities [Member] | US States and Political Subdivisions Debt Securities [Member] | Interest Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				0			0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)				0			0
Available-for-sale Securities [Member] | US States and Political Subdivisions Debt Securities [Member] | Other Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				0	0		0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)				0			0
Available-for-sale Securities [Member] | US Government Agencies Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		23,567		26,255	24,488		26,265
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		6		(135)	269		922
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	(134)		(147)	(370)		(404)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]			0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	(340)		(312)	(1,528)		(1,391)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3				0			0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3				0	0		0
Fair Value, end of period		23,251		25,833	23,251		25,833
Available-for-sale Securities [Member] | US Government Agencies Debt Securities [Member] | Investment Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		(116)		(122)	(348)		(367)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(116)		(122)	(348)		(367)
Available-for-sale Securities [Member] | US Government Agencies Debt Securities [Member] | Gain (Loss) on Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				0	0		0
Available-for-sale Securities [Member] | US Government Agencies Debt Securities [Member] | Interest Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							0
Available-for-sale Securities [Member] | US Government Agencies Debt Securities [Member] | Other Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings					0
Available-for-sale Securities [Member] | Foreign Government Debt Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		11,994		13,706	12,869		14,065
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(7)		48	(210)		336
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	(495)		0	(495)		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]			0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	0		(328)	(672)		(975)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0		0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		(6,853)		0	6,853		0
Available-for-sale Securities [Member] | Foreign Government Debt Securities [Member] | Investment Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		(1)		0	(1)		0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(1)		0	(1)		0
Available-for-sale Securities [Member] | Foreign Government Debt Securities [Member] | Gain (Loss) on Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				0	0		0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)				0			0
Available-for-sale Securities [Member] | Foreign Government Debt Securities [Member] | Interest Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				0			0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)				0			0
Available-for-sale Securities [Member] | Foreign Government Debt Securities [Member] | Other Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)				0			0
Available-for-sale Securities [Member] | Commercial Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, beginning of period		1,943		37,935	21,145		68,563
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		5		(94)	(57)		(2,453)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	0		0	0		(1,545)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]			0	(3,720)		25,976
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	(1)		(1)	(5,403)		(138)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0		0	0		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0		637	10,132		2,182
Fair Value, end of period		1,947		37,507	1,947		37,507
Available-for-sale Securities [Member] | Commercial Mortgage Backed Securities [Member] | Investment Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings		0		304	709		1,437
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		304	0		1,335
Available-for-sale Securities [Member] | Commercial Mortgage Backed Securities [Member] | Gain (Loss) on Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings				$ 0	(595)		(3,289)
Available-for-sale Securities [Member] | Commercial Mortgage Backed Securities [Member] | Interest Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings							$ 0
Available-for-sale Securities [Member] | Commercial Mortgage Backed Securities [Member] | Other Income [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings					0
Available-for-sale Securities [Member] | US Treasury and Government [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0			$ 0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		$ 0

[1] The amount reported within purchases, sales and settlements is the purchase price (for purchases) and the sales/settlement proceeds (for sales and settlements) based upon the actual date purchased or sold/settled. Items purchased and sold/settled in the same period are excluded from the rollforward. The Company had no issuances during the period.