Fair Value of Financial Instruments (Assets and Liabilities Measured on Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value (cost: $2,618,250 and $2,568,512)	$ 2,752,530		$ 2,826,001
Derivatives, index options	119,276		57,890
Total assets	2,871,806		2,883,891
Policyholder account balances	136,742	[1]	72,470	[1]
Other liabilities	4,553	[2]	2,718	[2]
Total liabilities	141,295		75,188
Percent of total	100.00%		100.00%
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, index options	0		0
Total assets	12,848		11,968
Policyholder account balances	0		0
Other liabilities	0		0
Total liabilities	0		0
Percent of total	0.40%		0.40%
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, index options	119,276		57,890
Total assets	2,858,958		2,871,923
Policyholder account balances	136,742		72,470
Other liabilities	0		0
Total liabilities	136,742		72,470
Percent of total	99.60%		99.60%
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, index options	0		0
Total assets	0		0
Policyholder account balances	0		0
Other liabilities	4,553		2,718
Total liabilities	4,553		2,718
Percent of total	0.00%		0.00%
Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value (cost: $2,618,250 and $2,568,512)	2,738,977		2,813,734
Debt Securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value (cost: $2,618,250 and $2,568,512)	0		0
Debt Securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value (cost: $2,618,250 and $2,568,512)	2,738,977		2,813,734
Debt Securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value (cost: $2,618,250 and $2,568,512)	0		0
Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value (cost: $2,618,250 and $2,568,512)	13,553		12,267
Equity Securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value (cost: $2,618,250 and $2,568,512)	12,848		11,968
Equity Securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value (cost: $2,618,250 and $2,568,512)	705		299
Equity Securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value (cost: $2,618,250 and $2,568,512)	0		0
Priced by Third-Party Vendors [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, index options	119,276		57,890
Priced by Third-Party Vendors [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, index options	0		0
Priced by Third-Party Vendors [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, index options	119,276		57,890
Priced by Third-Party Vendors [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, index options	0		0
Priced by Third-Party Vendors [Member] | Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value (cost: $2,618,250 and $2,568,512)	2,738,977		2,813,734
Priced by Third-Party Vendors [Member] | Debt Securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value (cost: $2,618,250 and $2,568,512)	0		0
Priced by Third-Party Vendors [Member] | Debt Securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value (cost: $2,618,250 and $2,568,512)	2,738,977		2,813,734
Priced by Third-Party Vendors [Member] | Debt Securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value (cost: $2,618,250 and $2,568,512)	0		0
Priced by Third-Party Vendors [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value (cost: $2,618,250 and $2,568,512)	13,553		12,267
Priced by Third-Party Vendors [Member] | Equity Securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value (cost: $2,618,250 and $2,568,512)	12,848		11,968
Priced by Third-Party Vendors [Member] | Equity Securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value (cost: $2,618,250 and $2,568,512)	705		299
Priced by Third-Party Vendors [Member] | Equity Securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value (cost: $2,618,250 and $2,568,512)	0		0
Priced Internally [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, index options	0		0
Priced Internally [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, index options	0		0
Priced Internally [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, index options	0		0
Priced Internally [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, index options	0		0
Priced Internally [Member] | Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value (cost: $2,618,250 and $2,568,512)	0		0
Priced Internally [Member] | Debt Securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value (cost: $2,618,250 and $2,568,512)	0		0
Priced Internally [Member] | Debt Securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value (cost: $2,618,250 and $2,568,512)	0		0
Priced Internally [Member] | Debt Securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value (cost: $2,618,250 and $2,568,512)	0		0
Priced Internally [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value (cost: $2,618,250 and $2,568,512)	0		0
Priced Internally [Member] | Equity Securities [Member] | Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value (cost: $2,618,250 and $2,568,512)	0		0
Priced Internally [Member] | Equity Securities [Member] | Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value (cost: $2,618,250 and $2,568,512)	0		0
Priced Internally [Member] | Equity Securities [Member] | Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale, at fair value (cost: $2,618,250 and $2,568,512)	$ 0		$ 0

[1] Represents the fair value of certain product-related embedded derivatives that were recorded at fair value.

[2] Represents the liability for share-based compensation.