Consolidated Balance Sheet (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis	$ 5,506,440	$ 5,189,994
Available-for-sale Equity Securities, Amortized Cost Basis	$ 67,437	$ 55,697
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	5,000,000	5,000,000
Preferred stock, shares outstanding	5,000,000	5,000,000
Common Class A
Common stock, shares authorized	88,500,000	88,500,000
Common stock, shares issued	25,559,881	26,502,769
Common stock, shares outstanding	25,559,881	26,502,769
Common Class B
Common stock, shares authorized	1,500,000	1,500,000
Common stock, shares issued	1,192,990	1,192,990
Common stock, shares outstanding	1,192,990	1,192,990