Derivative Instruments Fair Value of Derivative Instruments as Presented in the Consolidated Balance Sheets (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Derivatives, Fair Value [Line Items]
Derivative instruments	$ 415,258	$ 273,314
Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative instruments	461,610	318,907
Derivative Liabilities	3,384,922	2,576,089
Call Option [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative instruments	415,258	273,314
Option on Securities [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative instruments	43,105	45,593
Interest Rate Cap [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative instruments	3,247	0
Fixed Index Annuity Embedded Derivative Financial Instruments [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	3,337,556	2,530,496
2015 Notes Embedded Conversion Derivative [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	43,105	45,593
Interest Rate Swap [Member] | Not Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Derivative Liability, Fair Value, Gross Liability	$ 4,261	$ 0