CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	50,000,000	50,000,000
Preferred stock, shares issued	3,375,000	1,875,000
Preferred stock, shares outstanding	3,375,000	1,875,000
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares issued	648,317,395	643,557,048
Common stock, shares outstanding	527,259,920	553,391,311
Treasury stock, at cost; shares	121,057,475	90,165,737