Consolidated Balance Sheets (Parenthetical) - USD ($)
$ in Thousands
Dec. 31, 2016
Dec. 31, 2015
Investments:    
Securities held to maturity-fair value $ 7,337,611 $ 7,335,436
Securities available for sale-amortized cost 2,991,042 2,847,414
Mortgage loans-allowance for possible losses $ 650 $ 650
Common Class A    
STOCKHOLDERS’ EQUITY:    
Common stock, par value (usd per share) $ 0.01 $ 0.01
Common Stock, shares authorized 7,500,000 7,500,000
Common Stock, shares issued 3,436,166 3,436,166
Common Stock, shares outstanding 3,436,166 3,436,166
Common Class B    
STOCKHOLDERS’ EQUITY:    
Common stock, par value (usd per share) $ 0.01 $ 0.01
Common Stock, shares authorized 200,000 200,000
Common Stock, shares issued 200,000 200,000
Common Stock, shares outstanding 200,000 200,000