Fair Value of Assets and Liabilities (Changes in Level 3 Assets and Liabilities) (Details) - USD ($)		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2017	Dec. 31, 2016
Equity Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Fair Value, Asset Value, Beginning of period		$ 0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	13,962,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]	(6,759,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	(48,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		38,905,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0
Fair Value, Asset Value, End of period		33,460,000		$ 0
Corporate Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Fair Value, Asset Value, Beginning of period		1,337,272,000		1,272,253,000	$ 1,226,970,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(32,983,000)		(6,719,000)	10,022,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	509,134,000		408,995,000	312,720,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]	(106,005,000)		(89,248,000)	(60,399,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	(273,898,000)		(285,958,000)	(195,016,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		9,948,000		47,360,000	14,098,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		106,847,000		12,973,000	28,987,000
Fair Value, Asset Value, End of period		1,330,925,000		1,337,272,000	1,272,253,000
Canadian Provincial Governments [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Fair Value, Asset Value, Beginning of period		593,942,000		475,965,000	416,076,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(79,783,000)		104,797,000	47,692,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	0		0	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		0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0		0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0		0	0
Fair Value, Asset Value, End of period		528,124,000		593,942,000	475,965,000
Residential Mortgage Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Fair Value, Asset Value, Beginning of period		107,882,000		160,291,000	330,649,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(1,786,000)		2,341,000	(1,621,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	52,279,000		76,792,000	103,553,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]	(4,961,000)		(28,043,000)	(167,684,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	(4,633,000)		(18,988,000)	(38,495,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		3,031,000		9,100,000	1,728,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		145,140,000		93,994,000	65,091,000
Fair Value, Asset Value, End of period		6,855,000		107,882,000	160,291,000
Asset-backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Fair Value, Asset Value, Beginning of period		123,474,000		219,280,000	303,836,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(1,344,000)		7,044,000	(2,696,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	42,120,000		45,215,000	138,522,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]	(462,000)		0	(38,681,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	(57,476,000)		(87,328,000)	(61,770,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		73,289,000		85,152,000	56,105,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		86,163,000		147,910,000	177,938,000
Fair Value, Asset Value, End of period		95,572,000		123,474,000	219,280,000
US Treasury and Government [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Fair Value, Asset Value, Beginning of period		22,511,000		24,488,000	26,265,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(436,000)		19,000	39,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		418,000	[1]	465,000	508,000	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		0	[1]	0	0	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		(3,837,000)	[1]	(2,000,000)	(1,837,000)	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0		0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0		0	0
Fair Value, Asset Value, End of period		18,025,000		22,511,000	24,488,000
US States and Political Subdivisions Debt Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Fair Value, Asset Value, Beginning of period		41,203,000		41,666,000	38,342,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		66,000		(15,000)	962,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0	[1]	0	6,952,000	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		0	[1]	0	0	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		(494,000)	[1]	(843,000)	(599,000)	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		9,859,000		7,294,000	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		(40,441,000)		6,844,000	4,206,000
Fair Value, Asset Value, End of period		10,202,000		41,203,000	41,666,000
Debt Security, Government, Non-US [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Fair Value, Asset Value, Beginning of period		5,092,000		12,869,000	14,065,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(86,000)		(252,000)	110,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0	[1]	496,000	0	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		0	[1]	0	0	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		0	[1]	(672,000)	(1,306,000)	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0		0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0		7,348,000	0
Fair Value, Asset Value, End of period		5,006,000		5,092,000	12,869,000
Commercial Mortgage Backed Securities [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Fair Value, Asset Value, Beginning of period		3,234,000		21,145,000	68,563,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(65,000)		(71,000)	(5,887,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases		0	[1]	0	1,545,000	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales		(1,751,000)	[1]	(3,720,000)	(41,143,000)	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements		(5,000)	[1]	(5,404,000)	(552,000)	[1]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		1,752,000		1,302,000	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		(3,144,000)		10,132,000	2,182,000
Fair Value, Asset Value, End of period		22,000		3,234,000	21,145,000
Funds Withheld At Interest Embedded Derivatives [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Fair Value, Asset Value, Beginning of period		122,194,000		(22,529,000)	(76,698,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		0		0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	0		0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	0		0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0		0
Fair Value, Asset Value, End of period		109,597,000		122,194,000	(22,529,000)
Longevity Swap [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Fair Value, Asset Value, Beginning of period		40,659,000		26,958,000	14,996,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		(2,085,000)		4,343,000	(1,133,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	0		0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	0		0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		0		0
Fair Value, Asset Value, End of period		47,789,000		40,659,000	26,958,000
Short-term Investments [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Fair Value, Asset Value, Beginning of period		3,096,000		3,346,000	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Other Comprehensive Income (Loss)		1,000		11,000	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	[1]	2,624,000		3,703,000	3,365,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	[1]	(250,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Settlements	[1]	(461,000)		(335,000)	(19,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3		0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3		(2,782,000)		3,629,000
Fair Value, Asset Value, End of period		2,228,000		3,096,000	3,346,000
Interest Sensitive Contract Liabilities Embedded Derivatives [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Sales	[1]	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3		0
Fair Value, Liability Value, Beginning of period		(1,014,228,000)		(990,308,000)	(1,070,584,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Other Comprehensive Income (Loss)		0		0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases	[1]	(19,182,000)		(55,237,000)	(12,725,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	[1]	76,410,000		79,213,000	74,458,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3		0		0
Fair Value, Liability Value, End of period		(944,865,000)		(1,014,228,000)	(990,308,000)
Mortality Swap [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation Calculation [Roll Forward]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Sales	[1]	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3		0
Fair Value, Liability Value, Beginning of period		1,683,000		(2,462,000)	(2,619,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Other Comprehensive Income (Loss)		0		0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases	[1]	0		0	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	[1]	1,700,000		1,700,000	329,000
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3		0		0
Fair Value, Liability Value, End of period		369,000		1,683,000	(2,462,000)
Investment Income [Member] | Corporate Debt Securities [Member]
Fair Value Assets And Liabilities 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		(1,045,000)		(1,429,000)	(2,399,000)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(998,000)		(1,457,000)	(2,343,000)
Investment Income [Member] | Canadian Provincial Governments [Member]
Fair Value Assets And Liabilities 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		13,965,000		13,180,000	12,197,000
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		13,965,000		13,180,000	12,197,000
Investment Income [Member] | Residential Mortgage Backed Securities [Member]
Fair Value Assets And Liabilities 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		(129,000)		(346,000)	(595,000)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		3,000		(196,000)	(158,000)
Investment Income [Member] | Asset-backed Securities [Member]
Fair Value Assets And Liabilities 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		224,000		1,776,000	801,000
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		209,000		669,000	734,000
Investment Income [Member] | US Treasury and Government [Member]
Fair Value Assets And Liabilities 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		(423,000)		(461,000)	(487,000)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(417,000)		(461,000)	(487,000)
Investment Income [Member] | US States and Political Subdivisions Debt Securities [Member]
Fair Value Assets And Liabilities 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		9,000		(55,000)	215,000
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		8,000		(54,000)	215,000
Investment Income [Member] | Debt Security, Government, Non-US [Member]
Fair Value Assets And Liabilities 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		(1,000)	0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		(1,000)	0
Investment Income [Member] | Commercial Mortgage Backed Securities [Member]
Fair Value Assets And Liabilities 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		709,000	1,677,000
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0	1,552,000
Investment Related Gains Losses [Member] | Equity Securities [Member]
Fair Value Assets And Liabilities 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		(12,600,000)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(15,992,000)
Investment Related Gains Losses [Member] | Corporate Debt Securities [Member]
Fair Value Assets And Liabilities 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		(4,651,000)		4,991,000	(4,756,000)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(6,320,000)		(5,389,000)	(817,000)
Investment Related Gains Losses [Member] | Canadian Provincial Governments [Member]
Fair Value Assets And Liabilities 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	0
Investment Related Gains Losses [Member] | Residential Mortgage Backed Securities [Member]
Fair Value Assets And Liabilities 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		312,000		729,000	(2,153,000)
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		(346,000)	(231,000)
Investment Related Gains Losses [Member] | Asset-backed Securities [Member]
Fair Value Assets And Liabilities 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		1,910,000		245,000	1,101,000
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0	0
Investment Related Gains Losses [Member] | US Treasury and Government [Member]
Fair Value Assets And Liabilities 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		(208,000)		0	0
Investment Related Gains Losses [Member] | US States and Political Subdivisions Debt Securities [Member]
Fair Value Assets And Liabilities 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
Investment Related Gains Losses [Member] | Debt Security, Government, Non-US [Member]
Fair Value Assets And Liabilities 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
Investment Related Gains Losses [Member] | Commercial Mortgage Backed Securities [Member]
Fair Value Assets And Liabilities 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		1,000		(595,000)	(876,000)
Investment Related Gains Losses [Member] | Funds Withheld At Interest Embedded Derivatives [Member]
Fair Value Assets And Liabilities 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		(12,597,000)		144,723,000	54,169,000
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(12,597,000)		144,723,000	54,169,000
Investment Related Gains Losses [Member] | Longevity Swap [Member]
Fair Value Assets And Liabilities 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	0
Investment Related Gains Losses [Member] | Short-term Investments [Member]
Fair Value Assets And Liabilities 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	0
Investment Related Gains Losses [Member] | Interest Sensitive Contract Liabilities Embedded Derivatives [Member]
Fair Value Assets And 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		15,455,000		(32,166,000)	(7,834,000)
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(22,393,000)		23,472,000	(4,579,000)
Investment Related Gains Losses [Member] | Mortality Swap [Member]
Fair Value Assets And 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
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0	0
Interest Income [Member] | Equity Securities [Member]
Fair Value Assets And Liabilities 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
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0
Interest Income [Member] | Funds Withheld At Interest Embedded Derivatives [Member]
Fair Value Assets And Liabilities 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	0
Interest Income [Member] | Longevity Swap [Member]
Fair Value Assets And Liabilities 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	0
Interest Income [Member] | Short-term Investments [Member]
Fair Value Assets And Liabilities 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	0
Interest Income [Member] | Interest Sensitive Contract Liabilities Embedded Derivatives [Member]
Fair Value Assets And 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		(27,590,000)		80,062,000	(10,709,000)
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)		(48,819,000)		(159,276,000)	(63,748,000)
Interest Income [Member] | Mortality Swap [Member]
Fair Value Assets And 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
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0	0
Other Income [Member] | Equity Securities [Member]
Fair Value Assets And Liabilities 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
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0
Other Income [Member] | Funds Withheld At Interest Embedded Derivatives [Member]
Fair Value Assets And Liabilities 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	0
Other Income [Member] | Longevity Swap [Member]
Fair Value Assets And Liabilities 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		9,215,000		9,358,000	13,095,000
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		9,215,000		9,358,000	13,095,000
Other Income [Member] | Short-term Investments [Member]
Fair Value Assets And Liabilities 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	0
Other Income [Member] | Interest Sensitive Contract Liabilities Embedded Derivatives [Member]
Fair Value Assets And 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
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)		0		0	0
Other Income [Member] | Mortality Swap [Member]
Fair Value Assets And 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		(386,000)		921,000	172,000
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)		$ (386,000)		$ (921,000)	$ (172,000)

[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.