Employee Benefit Plans - Net Gratuity Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Retirement Benefits [Abstract]
Service cost	$ 493	$ 423	$ 980	$ 862
Interest cost	221	173	440	353
Expected return on plan assets	(144)	(118)	(286)	(242)
Amortization of actuarial gain	(40)	(38)	(79)	(77)
Net periodic benefit cost	$ 530	$ 440	$ 1,055	$ 896