Condensed Consolidated Statements of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2018	Jul. 01, 2017
Condensed Consolidated Statements of Income
Revenues	$ 217,106	$ 190,098	$ 422,490	$ 369,126
Cost of revenues	85,814	76,906	166,961	150,773
Gross margin	131,292	113,192	255,529	218,353
Operating expenses:
Research and development	59,495	52,432	114,323	104,756
Selling, general and administrative	53,796	39,826	99,490	79,981
Operating expenses	113,291	92,258	213,813	184,737
Operating income	18,001	20,934	41,716	33,616
Other income (expense):
Interest income and other, net	1,609	1,595	4,811	2,171
Interest expense	(4,888)	(4,699)	(9,771)	(4,501)
Income before income taxes	14,722	17,830	36,756	31,286
Provision (benefit) for income taxes	442	1,261	(3,929)	(709)
Net income	$ 14,280	$ 16,569	$ 40,685	$ 31,995
Earnings per share:
Basic (in dollars per share)	$ 0.33	$ 0.39	$ 0.94	$ 0.76
Diluted (in dollars per share)	$ 0.32	$ 0.38	$ 0.92	$ 0.74
Weighted-average common shares outstanding:
Basic (in shares)	43,312	42,478	43,138	42,287
Diluted (in shares)	44,294	43,178	44,106	43,104