Summary of Significant Accounting Policies - Narrative (Details)	12 Months Ended
	Dec. 31, 2017 USD ($) $ / shares shares	Mar. 06, 2017 USD ($)	Dec. 31, 2016 € / shares shares	Dec. 31, 2016 $ / shares shares
Class of Stock [Line Items]
Authorized share capital	$ 5,500,000
Ordinary shares, shares authorized (in shares) | shares	500,000,000		500,000,000	500,000,000
Ordinary shares, nominal value (in usd or euro per share) | (per share)	$ 0.01		€ 0.122	$ 0.01
Preferred shares, shares authorized (in shares) | shares	50,000,000		50,000,000	50,000,000
Preferred shares, nominal value (in usd per share) | $ / shares	$ 0.01			$ 0.01
Adjustment to reduce share premium		$ 317,254,000
Adjustment to increase available distributable reserves		$ 317,254,000
Ordinary shares
Class of Stock [Line Items]
Cross-border merger nominal value adjustment	$ (5,937,000)
Additional paid-in capital
Class of Stock [Line Items]
Cross-border merger nominal value adjustment	$ 0