Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Apr. 01, 2017
Operating Activities
Net Income	$ 26,405	$ 15,426
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation of property and equipment	3,704	3,596
Amortization of other intangible assets and other assets	6,427	6,752
Amortization of debt discount and debt issuance costs	3,169	869
Stock-based compensation expense	12,192	10,486
Deferred income taxes	(4,780)	(4,059)
Changes in operating assets and liabilities:
Accounts receivable	(3,307)	(1,252)
Inventories	(3,368)	(1,636)
Prepaid expenses and other assets	(17,169)	6,708
Accounts payable	13,030	5,565
Other current liabilities and income taxes	(9,463)	(2,944)
Deferred income, deferred revenue and returns liability	(2,599)	4,038
Other non-current liabilities	(1,849)	(1,536)
Net cash provided by operating activities	22,212	42,013
Investing Activities
Purchases of available-for-sale investments	(52,821)	(267,777)
Sales and maturities of available-for-sale investments	128,975	25,595
Purchases of property and equipment	(4,102)	(4,543)
Purchases of other assets	(4,698)	(1,446)
Acquisitions of business, net of cash acquired		(13,658)
Net cash provided by (used in) investing activities	67,354	(261,829)
Financing Activities
Proceeds from issuance of long-term debt, net		390,000
Payments on debt		(72,500)
Payment of taxes withheld for vested stock awards	(17,871)	(13,553)
Proceeds from the issuance of common stock	1,211	162
Net cash provided by (used in) financing activities	(16,660)	304,109
Increase in cash and cash equivalents	72,906	84,293
Cash and cash equivalents at beginning of period	269,366	141,106
Cash and cash equivalents at end of period	$ 342,272	$ 225,399