Condensed Consolidated Balance Sheets (Parenthetical) (USD $)	Jun. 30, 2012	Dec. 31, 2011
Condensed Consolidated Balance Sheets [Abstract]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	44,167,252	43,857,020
Common stock, shares outstanding	33,533,265	33,302,495
Treasury stock, at cost, shares	10,633,987	10,554,525