Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property and equipment	$ 204,518	$ 154,193
Less -- accumulated depreciation	125,395	96,197
Total	79,123	57,996
Computer hardware and software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	159,357	115,444
Furniture, fixtures and equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	22,242	17,556
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	19,229	16,628
Work-in-progress [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	$ 3,690	$ 4,565