Earnings Per Share - Schedule of Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Net income for the period - attributable to ordinary equity holders of the parent (in thousands)	$ 18,965	$ 24,253	$ 24,748	$ 18,954	$ 15,658	$ 25,817	$ 53,081	$ 26,754	$ 86,920	$ 121,310	$ 64,860
Weighted average number of ordinary shares (in thousands of shares) (in shares)									59,986	59,567	59,320
Basic EPS (in USD per share)	$ 0.32	$ 0.40	$ 0.41	$ 0.32	$ 0.27	$ 0.43	$ 0.89	$ 0.45	$ 1.45	$ 2.04	$ 1.09
Dilutive effect of share based payments (in thousands of shares) (in shares)									1,313	1,482	1,354
Weighted average number of diluted ordinary shares (in thousands of shares) (in shares)									61,300	61,049	60,674
Diluted EPS (in USD per share)	$ 0.31	$ 0.39	$ 0.40	$ 0.32	$ 0.25	$ 0.43	$ 0.87	$ 0.44	$ 1.42	$ 1.99	$ 1.07