Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Consolidated Balance Sheets [Abstract]
Preferred stock, par value
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, share issued
Preferred stock, shares outstanding
Common stock, par value
Common stock, shares authorized	225,000,000	225,000,000
Common stock, shares issued	104,482,271	106,075,576
Numbers of common shares outstanding options for purchase	104,482,271	106,075,576
Amortized cost	$ 2,130,029	$ 1,780,493