Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Consolidated Balance Sheets [Abstract]
Securities held-to-maturity, market value	$ 1,203,977	$ 837,359
Securities available-for-sale, amortized cost	$ 1,309,521	$ 2,005,330
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	258,000	258,000
Preferred stock, shares outstanding	258,000	258,000
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	82,860,122	82,739,348
Common stock, shares outstanding	78,652,557	78,531,783
Treasury stock, shares	4,207,565	4,207,565