Consolidated Statements of Shareholders' Equity - 6 months ended Jun. 30, 2017 - USD ($) $ in Thousands	Total	Ordinary Shares	Additional Paid-in Capital	Accumulated Deficit
Balance at Dec. 30, 2016	$ 141,659	$ 2	$ 196,049	$ (54,392)
Balance, Shares at Dec. 30, 2016		23,857,381
Ordinary shares issued from initial public offering, net of transaction costs	7,278	$ 1	7,277
Ordinary shares issued from initial public offering, net of transaction costs, shares		881,667
Ordinary shares issued from exercise of stock options	2,188		2,188
Ordinary shares issued from exercise of stock options, shares		264,697
Ordinary shares issued from vesting of restricted share units, Shares		52,443
Share-based compensation expense	913		913
Net income	22,700			22,700
Balance at Jun. 30, 2017	$ 174,738	$ 3	$ 206,427	$ (31,692)
Balance, Shares at Jun. 30, 2017		25,056,188