Restructuring Costs - Expenses Related to Restructuring Charges (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 4,468	$ 2,594	$ 2,369
Contract termination costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	0	(384)
Severance and other associated costs
Restructuring Cost and Reserve [Line Items]
Restructuring charges	4,468	648	1,585
Wind down costs of legacy platform
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 0	$ 1,946	$ 1,168