Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2015	Dec. 31, 2014
Consolidated Balance Sheets
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized (in shares)	4,000,000,000	4,000,000,000
Common stock, issued (in shares)	1,749,027,140	1,609,519,046
Common stock held in treasury, at cost (in shares)	139,134,205	18,129,715