Investment Operations Net Unrealized Gains (Losses) on Investments in Accumulated Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Net Unrealized Gains Losses [Line Items]
Net Unrealized appreciation, fixed maturities, Available-for-sale	$ 628,137	$ 380,556
Net Unrealized appreciation, Equity Securities, Available for sale	4,113	1,735
Net Unrealized Gains Losses on Investments	632,250	382,291
Assumed changes in amortization of DAC	172,320	104,875
Assumed changes in amortization patter of VIIF	15,346	12,281	5,697
Assumed changes in amortization patter of URR	13,554	8,312
Provision for deferred income taxes	160,333	95,688
Unrealized gains losses on investments net before equity investee	297,805	177,759
Net unrealized investment losses of equity investees	0	13
Net Unrealized gains losses on investments in Accumulated other comprehensive Income	$ 297,805	$ 177,746