Accrued Expenses and Other Current Liabilities - Summary of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accounts Payable and Accrued Liabilities, Current [Abstract]
Accrued expenses	$ 44,711	$ 43,235
Derivative instruments	3,204	555
Client liabilities	6,933	8,982
Other current liabilities	9,321	8,594
Accrued expenses and other current liabilities	$ 64,169	$ 61,366