Investments (Narrative) (Details) (USD $)	3 Months Ended																	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended
	Mar. 31, 2014 securities	Mar. 31, 2013	Dec. 31, 2013 securities	Mar. 31, 2014 Collateral Fixed Maturity Securities	Dec. 31, 2013 Collateral Fixed Maturity Securities	Mar. 31, 2014 Canadian Province Of Ontario Securities	Dec. 31, 2013 Canadian Province Of Ontario Securities	Mar. 31, 2014 Canadian Province Of Quebec Securities	Dec. 31, 2013 Canadian Province Of Quebec Securities	Mar. 31, 2014 Available For Sale Securities Amortized Cost [Member]	Dec. 31, 2013 Available For Sale Securities Amortized Cost [Member]	Mar. 31, 2014 Available For Sale Securities Fair Value Disclosure [Member]	Dec. 31, 2013 Available For Sale Securities Fair Value Disclosure [Member]	Mar. 31, 2013 Collateral Received Fixed Maturity Securities [Member]	Dec. 31, 2012 Collateral Received Fixed Maturity Securities [Member]	Mar. 31, 2014 Investment in mortgage loans	Dec. 31, 2013 Investment in mortgage loans	Mar. 31, 2014 Fixed maturity securities	Dec. 31, 2013 Fixed maturity securities	Mar. 31, 2014 Fixed maturity securities Non-investment grade securities	Dec. 31, 2013 Fixed maturity securities Non-investment grade securities	Mar. 31, 2014 Fixed maturity securities Corporate securities Non-investment grade securities	Dec. 31, 2013 Fixed maturity securities Corporate securities Non-investment grade securities
Investment Narrative [Line Items]
Available-for-sale Securities, Continuous Unrealized Loss Position, Aggregate Loss																		$ 174,984,000	$ 314,899,000	$ 13,641,000	$ 28,642,000	$ 6,607,000	$ 13,343,000
Available-for-sale Securities, Amortized Cost Basis	11,858,578,000		11,697,394,000	60,800,000	57,200,000
Securities held in trust										8,051,400,000	7,842,900,000	8,505,100,000	8,125,400,000
Proceeds From Sale Of Available For Sale Securities Sold At Loss	235,100,000	204,300,000
Available-for-sale Securities	12,518,300,000		12,110,755,000	62,600,000	58,000,000	1,245,700,000	1,222,300,000	1,419,000,000	1,389,100,000					107,200,000	94,100,000
Securities as a percentage of consolidated stockholder equity	10.00%		10.00%
Number of fixed maturity and equity securities in an unrealized loss position	1,046		1,396
Gross Unrealized Losses - 12 months or greater																		66,929,000	80,715,000	9,514,000	17,580,000	2,721,000	3,892,000
Net other-than-temporary impairment losses on fixed maturities recognized in earnings	(303,000)	(202,000)
Realized losses on fixed maturity and equity securities sold	(6,583,000)	(11,212,000)
Minimum percentage of fair value	100.00%
Securities Borrowed										184,500,000	93,000,000	183,400,000	93,000,000
Collateral Obtained Percent Of Fair Value Reverse Repurchase Agreements	100.00%
Securities pledged or received	300,500,000		300,300,000
Securities Sold under Agreements to Repurchase, Fair Value of Collateral	312,800,000		310,800,000
Securities Sold under Agreements to Repurchase, Collateral, Right to Reclaim Securities	349,700,000		344,200,000
Mortgage loans percentage of total investments	7.60%		7.70%
Maximum loan to value ratio on mortgage loan approval	75.00%
Mortgage loans on nonaccrual status																7,087,000	0
Policy loans, percentage of total investments	3.90%		3.80%
Funds withheld at interest, percentage of total investments	17.50%		17.80%
Funds withheld at interest	5,814,231,000		5,771,467,000
Funds withheld at interest, percentage attibutable to one client	$ 4,100,000,000
Other invested assets, percentage of total investments	3.70%		4.10%