Segment Information (Revenues and Long-lived Assets by Geographic Information) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 356,976	$ 344,141	$ 1,020,353	$ 966,466
Long-lived assets	672,539		672,539		$ 778,507
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	296,054	278,917	827,520	763,494
Long-lived assets	623,190		623,190		701,580
Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	17,728	16,825	51,298	51,178
Ireland
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	14,947	14,228	40,520	44,604
All other countries
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	28,247	$ 34,171	101,015	$ 107,190
Long-lived assets	$ 49,349		$ 49,349		$ 76,927