Segment Reporting and Foreign Operations - Long-lived Assets by Geographic Area (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 331,452	$ 292,820	$ 276,573
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	231,864	202,504	194,715
Ireland
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	45,283	45,671	47,337
Other foreign countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets	$ 54,305	$ 44,645	$ 34,521