Segment and Geographic Data, Revenue and assets by geographic area (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 29, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jul. 01, 2017	Apr. 01, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues	$ 775,892	$ 780,972	$ 761,030	$ 716,795	$ 673,462	$ 677,941	$ 643,164	$ 604,801	$ 3,034,689	$ 2,599,368	$ 2,317,328
Property and equipment, net	969,001				905,758				969,001	905,758
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues									743,647	590,839	541,106
Property and equipment, net	117,138				99,993				117,138	99,993
Germany [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues									982,082	837,258	743,500
Property and equipment, net	169,941				154,874				169,941	154,874
Other Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues									123,846	99,636	83,532
Property and equipment, net	121,964				130,523				121,964	130,523
Israel [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues									13,299	11,075	10,046
Property and equipment, net	103,675				102,890				103,675	102,890
Asia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Net revenues									1,171,815	1,060,560	$ 939,144
People's Republic of China [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	217,681				192,521				217,681	192,521
Republic of China (Taiwan) [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	145,644				122,080				145,644	122,080
Other Asia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	88,864				99,493				88,864	99,493
Other Geographic Area [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Property and equipment, net	$ 4,094				$ 3,384				$ 4,094	$ 3,384