Investments (Net Realized Investments Gains) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Investments [Line Items]
Net realized investment gains (losses)	$ 58,397	$ 57,089	$ 346,444
Trading securities, net realized gains	49,400	52,500	338,700
Parent Company [Member]
Investments [Line Items]
Net realized investment gains (losses)	(1,866)	1,420	6,373
Fixed Maturity Securities [Member]
Investments [Line Items]
Net realized investment gains (losses)	54,112	5,909	255,195
Trading securities, net realized gains	2,675	8,754	1,918
Equity Securities [Member]
Investments [Line Items]
Net realized investment gains (losses)	(4,854)	46,547	83,452
Trading securities, net realized gains	41,872	16,793	20,558
Short-Term Investments [Member]
Investments [Line Items]
Net realized investment gains (losses)	139	18	76
Trading securities, net realized gains	120	64	356
Option And Short Sale Transactions [Member]
Investments [Line Items]
Net realized investment gains (losses)	$ 9,000	$ 4,615	$ 7,721