Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities
Net income	$ 447,098	$ 487,848	$ 396,831
Adjustments to reconcile net income to net cash provided by operating activities:
Intangible asset amortization	201,498	152,065	101,994
Share-based compensation	102,441	106,900	98,771
Impairment charges	42,896	0	0
Depreciation	15,233	13,089	11,786
Acquired in-process research and development	0	85,000	23,750
Loss on disposal of assets	655	473	47
Deferred tax benefit	(88,815)	(225,591)	(41,163)
Provision for losses on accounts receivable and inventory	4,728	2,190	2,209
Loss on extinguishment and modification of debt	1,425	0	638
Amortization of debt discount and deferred financing costs	43,960	30,026	22,133
Other non-cash transactions	4,499	14,321	(3,741)
Changes in assets and liabilities:
Accounts receivable	(40,132)	12,278	(25,603)
Inventories	(18,512)	(8,667)	(17,024)
Prepaid expenses and other current assets	6,697	(26,874)	(15,700)
Other non-current assets	(320)	119	267
Accounts payable	17,040	214	361
Accrued liabilities	71,208	(6,578)	11,989
Income taxes payable	(19,735)	16,331	2,962
Deferred revenue	(7,497)	21,009	(1,315)
Other non-current liabilities	14,537	18,934	23,199
Net cash provided by operating activities	798,904	693,087	592,391
Investing activities
Acquisition of investments	(1,165,915)	(385,000)	(132,181)
Proceeds from maturity of investments	855,000	230,000	66,906
Acquired in-process research and development	0	(85,000)	(23,750)
Purchases of property, plant and equipment	(20,370)	(28,950)	(9,687)
Acquisitions, net of cash acquired	0	0	(1,502,443)
Acquisition of intangible assets	(111,100)	0	(150,000)
Net proceeds from sale of assets	47,898	0	0
Net cash used in investing activities	(394,487)	(268,950)	(1,751,155)
Financing activities
Net proceeds from issuance of debt	0	559,393	994,647
Proceeds from employee equity incentive and purchase plans	93,337	31,824	24,174
Share repurchases	(523,672)	(98,799)	(278,296)
Payment of employee withholding taxes related to share-based awards	(17,925)	(18,589)	(21,234)
Repayments of long-term debt	(25,717)	(36,094)	(28,304)
Payment of debt modification costs	(6,406)	0	0
Repayments under revolving credit facility	0	(850,000)	(150,000)
Proceeds from tenant improvement allowance on build-to-suit lease	1,253	3,154	0
Net cash provided by (used in) financing activities	(479,130)	(409,111)	540,987
Effect of exchange rates on cash and cash equivalents	(1,700)	5,046	(5,045)
Net increase (decrease) in cash and cash equivalents	(76,413)	20,072	(622,822)
Cash and cash equivalents, at beginning of period	386,035	365,963	988,785
Cash and cash equivalents, at end of period	309,622	386,035	365,963
Supplemental disclosure of cash flow information:
Cash paid for interest	42,706	44,609	39,898
Cash paid for income taxes	164,217	174,124	160,306
Non-cash investing activities:
Amounts capitalized in connection with facility lease obligations	$ 27,747	$ 40,970	$ 23,799