Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2019	Dec. 31, 2018
Consolidated Balance Sheets
Ordinary stock, nominal value (in dollars per share)	$ 0.01	$ 0.01
Ordinary stock, authorized shares	1,000,000,000	1,000,000,000
Ordinary stock, issued shares	71,335,980	67,019,094
Ordinary stock, outstanding shares	71,335,980	67,019,094
Preferred stock, par value (in dollars per share)	$ 0.01
Preferred stock, authorized shares	100,000,000
Preferred stock, issued shares	0
Preferred stock, outstanding shares	0