Fair Value of Assets and Liabilities Fair Value of Assets and Liabilities (Quantitative Information for Level 3 Inputs) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Discounted Cash Flow [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Interest-sensitive contract liabilities - embedded derivatives - indexed annuities	$ 858,270	$ 838,670
Interest-sensitive contract liabilities - embedded derivatives - variable annuities	53,717	30,055
Discounted Cash Flow [Member] | Mortality [Member] | Minimum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Interest-sensitive contract liabilities - embedded derivatives - indexed annuities Unobservable Input Range	0.00%	0.00%
Interest-sensitive contract liabilities - embedded derivatives - variable annuities Unobservable Input Range	0.00%	0.00%
Discounted Cash Flow [Member] | Mortality [Member] | Maximum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Interest-sensitive contract liabilities - embedded derivatives - indexed annuities Unobservable Input Range	100.00%	100.00%
Interest-sensitive contract liabilities - embedded derivatives - variable annuities Unobservable Input Range	100.00%	100.00%
Discounted Cash Flow [Member] | Mortality [Member] | Weighted Average [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Interest-sensitive contract liabilities - embedded derivatives - indexed annuities Unobservable Input Range	2.00%	2.00%
Interest-sensitive contract liabilities - embedded derivatives - variable annuities Unobservable Input Range	2.00%	2.00%
Discounted Cash Flow [Member] | Lapse [Member] | Minimum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Interest-sensitive contract liabilities - embedded derivatives - indexed annuities Unobservable Input Range	0.00%	0.00%
Interest-sensitive contract liabilities - embedded derivatives - variable annuities Unobservable Input Range	0.00%	0.00%
Discounted Cash Flow [Member] | Lapse [Member] | Maximum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Interest-sensitive contract liabilities - embedded derivatives - indexed annuities Unobservable Input Range	35.00%	35.00%
Interest-sensitive contract liabilities - embedded derivatives - variable annuities Unobservable Input Range	25.00%	25.00%
Discounted Cash Flow [Member] | Lapse [Member] | Weighted Average [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Interest-sensitive contract liabilities - embedded derivatives - indexed annuities Unobservable Input Range	7.00%	7.00%
Interest-sensitive contract liabilities - embedded derivatives - variable annuities Unobservable Input Range	7.00%	6.00%
Discounted Cash Flow [Member] | Withdrawal [Member] | Minimum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Interest-sensitive contract liabilities - embedded derivatives - indexed annuities Unobservable Input Range	0.00%	0.00%
Interest-sensitive contract liabilities - embedded derivatives - variable annuities Unobservable Input Range	0.00%	0.00%
Discounted Cash Flow [Member] | Withdrawal [Member] | Maximum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Interest-sensitive contract liabilities - embedded derivatives - indexed annuities Unobservable Input Range	5.00%	5.00%
Interest-sensitive contract liabilities - embedded derivatives - variable annuities Unobservable Input Range	7.00%	7.00%
Discounted Cash Flow [Member] | Withdrawal [Member] | Weighted Average [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Interest-sensitive contract liabilities - embedded derivatives - indexed annuities Unobservable Input Range	3.00%	3.00%
Interest-sensitive contract liabilities - embedded derivatives - variable annuities Unobservable Input Range	3.00%	3.00%
Discounted Cash Flow [Member] | Own Credit [Member] | Minimum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Interest-sensitive contract liabilities - embedded derivatives - variable annuities Unobservable Input Range	0.00%	0.00%
Discounted Cash Flow [Member] | Own Credit [Member] | Maximum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Interest-sensitive contract liabilities - embedded derivatives - variable annuities Unobservable Input Range	1.00%	1.00%
Discounted Cash Flow [Member] | Own Credit [Member] | Weighted Average [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Interest-sensitive contract liabilities - embedded derivatives - variable annuities Unobservable Input Range	1.00%	1.00%
Discounted Cash Flow [Member] | Option Budget Projection [Member] | Minimum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Interest-sensitive contract liabilities - embedded derivatives - indexed annuities Unobservable Input Range	2.00%	2.00%
Discounted Cash Flow [Member] | Option Budget Projection [Member] | Maximum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Interest-sensitive contract liabilities - embedded derivatives - indexed annuities Unobservable Input Range	4.00%	4.00%
Discounted Cash Flow [Member] | Option Budget Projection [Member] | Weighted Average [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Interest-sensitive contract liabilities - embedded derivatives - indexed annuities Unobservable Input Range	3.00%	3.00%
Discounted Cash Flow [Member] | Long Term Volatility [Member] | Minimum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Interest-sensitive contract liabilities - embedded derivatives - variable annuities Unobservable Input Range	0.00%	0.00%
Discounted Cash Flow [Member] | Long Term Volatility [Member] | Maximum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Interest-sensitive contract liabilities - embedded derivatives - variable annuities Unobservable Input Range	27.00%	27.00%
Discounted Cash Flow [Member] | Long Term Volatility [Member] | Weighted Average [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Interest-sensitive contract liabilities - embedded derivatives - variable annuities Unobservable Input Range	10.00%	10.00%
Total Return Swap [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Funds withheld at interest - embedded derivatives	(99,029)	176,270
Total Return Swap [Member] | Mortality [Member] | Minimum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Funds withheld at interest - embedded derivatives Unobservable Input Range	0.00%	0.00%
Total Return Swap [Member] | Mortality [Member] | Maximum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Funds withheld at interest - embedded derivatives Unobservable Input Range	100.00%	100.00%
Total Return Swap [Member] | Mortality [Member] | Weighted Average [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Funds withheld at interest - embedded derivatives Unobservable Input Range	2.00%	2.00%
Total Return Swap [Member] | Lapse [Member] | Minimum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Funds withheld at interest - embedded derivatives Unobservable Input Range	0.00%	0.00%
Total Return Swap [Member] | Lapse [Member] | Maximum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Funds withheld at interest - embedded derivatives Unobservable Input Range	35.00%	35.00%
Total Return Swap [Member] | Lapse [Member] | Weighted Average [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Funds withheld at interest - embedded derivatives Unobservable Input Range	7.00%	7.00%
Total Return Swap [Member] | Withdrawal [Member] | Minimum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Funds withheld at interest - embedded derivatives Unobservable Input Range	0.00%	0.00%
Total Return Swap [Member] | Withdrawal [Member] | Maximum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Funds withheld at interest - embedded derivatives Unobservable Input Range	5.00%	5.00%
Total Return Swap [Member] | Withdrawal [Member] | Weighted Average [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Funds withheld at interest - embedded derivatives Unobservable Input Range	3.00%	3.00%
Total Return Swap [Member] | Own Credit [Member] | Minimum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Funds withheld at interest - embedded derivatives Unobservable Input Range	0.00%	0.00%
Total Return Swap [Member] | Own Credit [Member] | Maximum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Funds withheld at interest - embedded derivatives Unobservable Input Range	1.00%	1.00%
Total Return Swap [Member] | Own Credit [Member] | Weighted Average [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Funds withheld at interest - embedded derivatives Unobservable Input Range	1.00%	1.00%
Total Return Swap [Member] | Crediting Rate [Member] | Minimum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Funds withheld at interest - embedded derivatives Unobservable Input Range	2.00%	2.00%
Total Return Swap [Member] | Crediting Rate [Member] | Maximum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Funds withheld at interest - embedded derivatives Unobservable Input Range	4.00%	4.00%
Total Return Swap [Member] | Crediting Rate [Member] | Weighted Average [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Funds withheld at interest - embedded derivatives Unobservable Input Range	3.00%	3.00%
Market Comparable Securities [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
State And Political Subdivision Securities	21,689
Corporate Securities	267,015
Financial Instruments, Owned, US Government and Agency Obligations, at Fair Value	34,693
Market Comparable Securities [Member] | Liquidity Premium [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
State And Political Subdivision Securities		29,024
Corporate Securities		312,887
Short-term Investments		$ 37,539
Market Comparable Securities [Member] | Liquidity Premium [Member] | Minimum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
US Government And Agencies Securities Unobservable Input Range	0.00%
Corporate Securities Unobservable Input Range	0.00%	0.00%
Short Term Investments Unobservable Input Range		0.00%
State And Political Subdivision Securities Unobservable Input Range	1.00%	1.00%
Market Comparable Securities [Member] | Liquidity Premium [Member] | Maximum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
US Government And Agencies Securities Unobservable Input Range	1.00%
Corporate Securities Unobservable Input Range	2.00%	2.00%
Short Term Investments Unobservable Input Range		1.00%
State And Political Subdivision Securities Unobservable Input Range	1.00%	1.00%
Market Comparable Securities [Member] | Liquidity Premium [Member] | Weighted Average [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
US Government And Agencies Securities Unobservable Input Range	1.00%
Corporate Securities Unobservable Input Range	1.00%	1.00%
Short Term Investments Unobservable Input Range		1.00%
State And Political Subdivision Securities Unobservable Input Range	1.00%	1.00%