Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Investments:
Securities held to maturity-fair value	$ 6,503,627	$ 6,082,330
Securities available for sale-amortized cost	2,568,512	2,422,650
Mortgage loans-allowance for possible losses	$ 650	$ 4,571
Common Class A [Member]
STOCKHOLDERS’ EQUITY:
Common stock, par value	$ 1	$ 1
Common Stock, shares authorized	7,500,000	7,500,000
Common Stock, shares issued	3,434,766	3,434,766
Common Stock, shares outstanding	3,434,766	3,434,766
Common Class B [Member]
STOCKHOLDERS’ EQUITY:
Common stock, par value	$ 1	$ 1
Common Stock, shares authorized	200,000	200,000
Common Stock, shares issued	200,000	200,000
Common Stock, shares outstanding	200,000	200,000