Stock Compensation - Share activity (Details)	9 Months Ended
	Sep. 30, 2017 shares
Stock Compensation
Beginning balance, Shares outstanding	188,848,752
Exercise of stock options and issuance under ESPP	2,643,324
Settlement of employee restricted stock units and performance shares	285,958
Conversion of convertible senior notes	14,296,332
Public issuance of common stock	4,945,000
Ending balance, Shares outstanding	211,019,366