Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Securities held-to-maturity ,fair value	$ 3,321,317	$ 3,130,546
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	3,000,000	3,000,000
Common stock par value	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	90,728,276	90,709,350
Treasury stock ,shares	3,269,141	3,493,915
Series A Preferred Stock [Member]
Preferred stock, shares issued	28,939	28,939
Preferred stock, shares outstanding	28,939	28,939