Consolidated Statements of Changes in Equity (Parenthetical) - $ / shares	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Common stock, par value (usd per share)	$ 0.01	$ 0.01
Contingent convertible preferred stock, par value (usd per share)	0.01	0.01
Treasury stock, par value (usd per share)	0.01	0.01
Common Stock
Common stock, par value (usd per share)	0.01	0.01	$ 0.01
Contingent Convertible Preferred Stock
Contingent convertible preferred stock, par value (usd per share)	0.01	0.01	0.01
Treasury Stock
Treasury stock, par value (usd per share)	$ 0.01	$ 0.01	$ 0.01