Revenues (Revenues by Disaggregated Category) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 28, 2018	Sep. 28, 2018	Jun. 29, 2018	Mar. 30, 2018	Dec. 29, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 28, 2018	Dec. 29, 2017	Dec. 30, 2016
Disaggregation of Revenue [Line Items]
Total revenues	$ 228,602	$ 225,397	$ 186,108	$ 213,719	$ 120,072	$ 152,510	$ 99,008	$ 80,887	$ 853,826	$ 452,477	$ 191,454
Net product revenues
Disaggregation of Revenue [Line Items]
Total revenues									619,279	349,008	135,375
Gross product revenues
Disaggregation of Revenue [Line Items]
Total revenues									738,529	402,569	151,499
Discounts and allowances
Disaggregation of Revenue [Line Items]
Total revenues									119,250	53,561	16,124
Total collaboration revenues
Disaggregation of Revenue [Line Items]
Total revenues									234,547	103,469	56,079
License revenues
Disaggregation of Revenue [Line Items]
Total revenues									192,188	96,637	56,286
Research and development services revenues
Disaggregation of Revenue [Line Items]
Total revenues									39,501	8,737	0
Other collaboration revenues
Disaggregation of Revenue [Line Items]
Total revenues									$ 2,858	$ (1,905)	$ (207)