Consolidated Balance Sheets (Parenthetical) (USD $)	Mar. 31, 2012	Dec. 31, 2011
Consolidated Balance Sheets [Abstract]
Common stock, par value
Common stock, shares authorized	180,000,000	180,000,000
Common stock, shares issued	92,262,236	92,267,256
Common stock, shares outstanding	92,262,236	92,267,256
Treasury stock, shares	16,195	0