Fair Value Disclosures (Details 1) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012
Discounted Cash Flow [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Reinsurance ceded receivable - embedded derivatives	$ 3,514
Interest-sensitive contract liabilities - embedded derivatives - indexed annuities	772,939
Interest-sensitive contract liabilities - embedded derivatives - variable annuities	130,343
Discounted Cash Flow [Member] | Mortality [Member] | Minimum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Reinsurance ceded receivable - embedded derivatives Unobservable Input Range	0.00%
Interest-sensitive contract liabilities - embedded derivatives - indexed annuities Unobservable Input Range	0.00%
Interest-sensitive contract liabilities - embedded derivatives - variable annuities Unobservable Input Range	0.00%
Discounted Cash Flow [Member] | Mortality [Member] | Maximum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Reinsurance ceded receivable - embedded derivatives Unobservable Input Range	100.00%
Interest-sensitive contract liabilities - embedded derivatives - indexed annuities Unobservable Input Range	100.00%
Interest-sensitive contract liabilities - embedded derivatives - variable annuities Unobservable Input Range	100.00%
Discounted Cash Flow [Member] | Mortality [Member] | Weighted Average [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Reinsurance ceded receivable - embedded derivatives Unobservable Input Range	8.00%
Interest-sensitive contract liabilities - embedded derivatives - indexed annuities Unobservable Input Range	1.00%
Interest-sensitive contract liabilities - embedded derivatives - variable annuities Unobservable Input Range	1.00%
Discounted Cash Flow [Member] | Lapse [Member] | Minimum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Reinsurance ceded receivable - embedded derivatives Unobservable Input Range	14.00%
Interest-sensitive contract liabilities - embedded derivatives - indexed annuities Unobservable Input Range	0.00%
Interest-sensitive contract liabilities - embedded derivatives - variable annuities Unobservable Input Range	0.00%
Discounted Cash Flow [Member] | Lapse [Member] | Maximum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Reinsurance ceded receivable - embedded derivatives Unobservable Input Range	16.00%
Interest-sensitive contract liabilities - embedded derivatives - indexed annuities Unobservable Input Range	35.00%
Interest-sensitive contract liabilities - embedded derivatives - variable annuities Unobservable Input Range	25.00%
Discounted Cash Flow [Member] | Lapse [Member] | Weighted Average [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Reinsurance ceded receivable - embedded derivatives Unobservable Input Range	15.00%
Interest-sensitive contract liabilities - embedded derivatives - indexed annuities Unobservable Input Range	4.00%
Interest-sensitive contract liabilities - embedded derivatives - variable annuities Unobservable Input Range	5.00%
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%
Interest-sensitive contract liabilities - embedded derivatives - variable annuities Unobservable Input Range	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%
Interest-sensitive contract liabilities - embedded derivatives - variable annuities Unobservable Input Range	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	4.00%
Interest-sensitive contract liabilities - embedded derivatives - variable annuities Unobservable Input Range	4.00%
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%
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%
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%
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%
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%
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%
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%
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%
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	16.00%
Total Return Swap [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Funds withheld at interest - embedded derivatives	(370,884)
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%
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%
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	1.00%
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%
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%
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	4.00%
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%
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%
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	4.00%
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%
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%
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	0.00%
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%
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%
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%
Market Comparable Securities [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
State And Political Subdivision Securities	5,239
Corporate Securities	20,101
Market Comparable Securities [Member] | Liquidity Premium [Member] | Minimum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
State And Political Subdivision Securities Unobservable Input Range	1.00%
Corporate Securities Unobservable Input Range	1.00%
Market Comparable Securities [Member] | Liquidity Premium [Member] | Maximum [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
State And Political Subdivision Securities Unobservable Input Range	1.00%
Corporate Securities Unobservable Input Range	2.00%
Market Comparable Securities [Member] | Liquidity Premium [Member] | Weighted Average [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
State And Political Subdivision Securities Unobservable Input Range	1.00%
Corporate Securities Unobservable Input Range	2.00%
Net Asset Value [Member]
Unobservable Inputs Used In Level 3 Fair Value Measurements [Line Items]
Private Equity Securities	$ 9,852