Consolidated Balance Sheets (Parenthetical)	Dec. 31, 2016 $ / shares shares	Dec. 31, 2016 € / shares shares	Dec. 31, 2015 $ / shares shares	Dec. 31, 2015 € / shares shares
Statement Of Financial Position [Abstract]
Ordinary shares, par value | $ / shares	$ 0.001		$ 0.001
Ordinary shares, shares authorized	350,000,000	350,000,000	350,000,000	350,000,000
Ordinary shares, shares issued	13,420,927	13,420,927	13,335,477	13,335,477
Ordinary shares, shares outstanding	13,420,927	13,420,927	13,335,477	13,335,477
Deferred ordinary shares, par value | (per share)	$ 1.35	€ 1.00	$ 1.35	€ 1.00
Deferred ordinary shares, shares authorized	39,994	39,994	39,994	39,994
Deferred ordinary shares, shares issued	39,994	39,994	39,994	39,994
Deferred ordinary shares, shares outstanding	39,994	39,994	39,994	39,994
Preferred shares, par value | $ / shares	$ 0.001		$ 0.001
Preferred shares, shares authorized	50,000,000	50,000,000	50,000,000	50,000,000
Preferred shares, shares issued	0	0	0	0
Preferred shares, shares outstanding	0	0	0	0