Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Securities held-to-maturity, fair value	3,130,546	3,141,775
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	90,709,350	90,688,879
Treasury stock, shares	3,493,915	3,830,050
Series A Preferred Stock [Member]
Preferred stock, shares issued	28,939	28,939
Preferred stock, shares outstanding	28,939	28,939