Revenue Recognition (Disaggregation of Revenue by Principal Geographic Area, Based on Customers' Domiciles) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Total revenue	$ 2,706,655	$ 2,406,908	$ 2,213,242
Americas
Disaggregation of Revenue [Line Items]
Total revenue	1,850,485	1,651,581	1,503,084
United States
Disaggregation of Revenue [Line Items]
Total revenue	1,691,224	1,495,516	1,357,909
Canada
Disaggregation of Revenue [Line Items]
Total revenue	107,398	99,550	94,206
Latin America
Disaggregation of Revenue [Line Items]
Total revenue	51,863	56,515	50,969
Europe, the Middle East and Africa
Disaggregation of Revenue [Line Items]
Total revenue	562,765	498,439	472,070
Germany
Disaggregation of Revenue [Line Items]
Total revenue	119,353	104,081	100,459
United Kingdom
Disaggregation of Revenue [Line Items]
Total revenue	90,156	90,969	87,807
France
Disaggregation of Revenue [Line Items]
Total revenue	74,814	64,767	60,319
Italy
Disaggregation of Revenue [Line Items]
Total revenue	42,817	39,725	36,956
Spain
Disaggregation of Revenue [Line Items]
Total revenue	39,265	36,439	33,687
Switzerland
Disaggregation of Revenue [Line Items]
Total revenue	24,850	20,855	19,875
Netherlands
Disaggregation of Revenue [Line Items]
Total revenue	23,461	19,397	18,090
Other
Disaggregation of Revenue [Line Items]
Total revenue	148,049	122,206	114,877
Asia Pacific Region
Disaggregation of Revenue [Line Items]
Total revenue	293,405	256,888	238,088
Australia
Disaggregation of Revenue [Line Items]
Total revenue	79,629	71,069	63,386
Japan
Disaggregation of Revenue [Line Items]
Total revenue	74,725	67,246	60,213
China
Disaggregation of Revenue [Line Items]
Total revenue	70,845	57,518	57,621
Other
Disaggregation of Revenue [Line Items]
Total revenue	$ 68,206	$ 61,055	$ 56,868