Consolidated Balance Sheets (Parenthetical) (USD $)	Jun. 30, 2014	Dec. 31, 2013
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest [Abstract]
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	6,000,000	6,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	600,000,000	600,000,000
Common Stock, Shares, Issued	216,616,466	215,578,445
Treasury Stock, Shares	91,619,119	87,206,462