Revenue Recognition (Disaggregation of Revenue by Principal Geographic Area, Based on Customers' Domiciles) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Total revenue	$ 605,446	$ 605,303	$ 620,103	$ 576,056	$ 549,386	$ 545,448	$ 580,752	$ 537,656	$ 2,406,908	$ 2,213,242	$ 1,969,058
Americas
Disaggregation of Revenue [Line Items]
Total revenue									1,651,581	1,503,084	1,334,258
United States
Disaggregation of Revenue [Line Items]
Total revenue									1,495,516	1,357,909	1,203,547
Canada
Disaggregation of Revenue [Line Items]
Total revenue									99,550	94,206	83,818
Latin America
Disaggregation of Revenue [Line Items]
Total revenue									56,515	50,969	46,893
Europe, the Middle East and Africa
Disaggregation of Revenue [Line Items]
Total revenue									498,439	472,070	419,424
Germany
Disaggregation of Revenue [Line Items]
Total revenue									104,081	100,459	88,328
United Kingdom
Disaggregation of Revenue [Line Items]
Total revenue									90,969	87,807	80,149
France
Disaggregation of Revenue [Line Items]
Total revenue									64,767	60,319	55,993
Italy
Disaggregation of Revenue [Line Items]
Total revenue									39,725	36,956	31,889
Spain
Disaggregation of Revenue [Line Items]
Total revenue									36,439	33,687	28,866
Switzerland
Disaggregation of Revenue [Line Items]
Total revenue									20,855	19,875	17,913
Netherlands
Disaggregation of Revenue [Line Items]
Total revenue									19,397	18,090	15,877
Other
Disaggregation of Revenue [Line Items]
Total revenue									122,206	114,877	100,409
Asia Pacific Region
Disaggregation of Revenue [Line Items]
Total revenue									256,888	238,088	215,376
Australia
Disaggregation of Revenue [Line Items]
Total revenue									71,069	63,386	56,994
Japan
Disaggregation of Revenue [Line Items]
Total revenue									67,246	60,213	53,344
China
Disaggregation of Revenue [Line Items]
Total revenue									57,518	57,621	55,810
Other
Disaggregation of Revenue [Line Items]
Total revenue									$ 61,055	$ 56,868	$ 49,228