Consolidated Balance Sheets Parenthetical (USD $)	Dec. 31, 2011	Dec. 31, 2010
Consolidated Balance Sheets - Parenthetical [Abstract]
Preferred stock, par value	$ 0.01
Preferred stock, shares authorized	2,000,000
Preferred stock, outstanding	0
Common stock, par value	$ 0.01
Common stock, shares authorized	350,000,000
Common stock, shares issued	98,684,000	97,122,000
Common stock, outstanding	96,678,000	95,088,000
Treasury stock, shares	2,006,000	2,034,000