Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data	Sep. 30, 2011	Dec. 31, 2010
Investments:
Securities held to maturity, fair value	$ 5,943,190	$ 5,259,332
Securities available for sale, amortized cost	2,386,834	2,221,579
Mortgage loans-allowance for possible losses	$ 4,001	$ 3,962
Common Class A [Member]
STOCKHOLDERS’ EQUITY:
Common Stock, Par or Stated Value Per Share	$ 1	$ 1
Common Stock, Shares Authorized	7,500,000	7,500,000
Common Stock, Shares, Issued	3,434,763	3,429,241
Common Stock, Shares, Outstanding	3,434,763	3,429,241
Common Class B [Member]
STOCKHOLDERS’ EQUITY:
Common Stock, Par or Stated Value Per Share	$ 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