Equity (Details) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Summary of preferred stock
Preferred stock, shares authorized	8,000	8,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Summary of common stock
Common stock, shares authorized	1,000,000	1,000,000
Common stock, shares issued	254,237	255,633
Common stock, shares outstanding	236,582	242,115
Series A
Summary of preferred stock
Preferred stock, shares authorized	1,750	1,750
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Series X Junior Participating
Summary of preferred stock
Preferred stock, shares authorized	1,000	1,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Undesignated
Summary of preferred stock
Preferred stock, shares authorized	5,250	5,250
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0