6. Derivative Instruments Fair Value (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Interest rate swaps
Fair Value Notional Amount	$ 116,000	$ 101,000
Fair Value Assets	12,466	10,792
Fair Value Liabilities	4,654	3,472
Variance Swaps
Fair Value Notional Amount	935	935
Fair Value Assets	0	3,202
Fair Value Liabilities	1,310	0
Swaptions
Fair Value Notional Amount	25,000	25,000
Fair Value Assets	60	254
Fair Value Liabilities	0	0
Put options
Fair Value Notional Amount	200,000	200,000
Fair Value Assets	50,950	54,833
Fair Value Liabilities	0	0
Call options
Fair Value Notional Amount	635,481	354,933
Fair Value Assets	50,754	27,956
Fair Value Liabilities	33,515	18,985
Equity futures
Fair Value Notional Amount	200,529	66,347
Fair Value Assets	15,418	16,185
Fair Value Liabilities	0	0
Total non-hedging derivative instruments
Fair Value Notional Amount	1,177,945	748,215
Fair Value Assets	129,648	113,222
Fair Value Liabilities	$ 39,479	$ 22,457