CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2020	Dec. 31, 2019
Stockholders' equity
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	800,000,000	800,000,000
Common stock, shares issued (in shares)	594,890,000	421,508,000
Common stock, shares outstanding (in shares)	579,122,000	415,048,000
Treasury stock (in shares)	15,768,000	6,460,000