Consolidated Statements of Cash Flows $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Operating Activities
Net income (loss)	$ 575,667	$ (20,719)	$ 536,112
Loss (income) from discontinued operations	0	42,704	(66,257)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Amortization and impairment of intangible assets	62,913	82,878	70,494
Depreciation and amortization of property and equipment	78,983	87,137	107,954
Amortization of debt discount and transaction costs	39,099	38,298	37,085
Amortization of deferred costs	38,144	0	0
Stock-based compensation expense	203,619	165,120	152,739
Deferred income tax (benefit) expense	(13,156)	94,158	(21,654)
Excess tax benefit from stock-based compensation			(16,049)
Effects of exchange rate changes on monetary assets and liabilities denominated in foreign currencies	7,950	(7,645)	5,189
Other non-cash items	11,872	11,924	8,618
Total adjustments to reconcile net income (loss) to net cash provided by operating activities	429,424	471,870	344,376
Changes in operating assets and liabilities, net of the effects of acquisitions:
Accounts receivable	18,703	(33,904)	(61,662)
Inventories	(8,239)	(2,545)	(4,133)
Prepaid expenses and other current assets	(7,855)	(18,327)	(12,077)
Other assets	(33,638)	2,116	(2,747)
Income taxes, net	(56,988)	318,795	42,431
Accounts payable	6,804	(7,238)	(16,365)
Accrued expenses and other current liabilities	36,967	34,886	22,650
Deferred revenues	69,499	174,426	142,381
Other liabilities	5,001	2,282	22,459
Total changes in operating assets and liabilities, net of the effects of acquisitions	30,254	470,491	132,937
Net cash provided by operating activities of continuing operations	1,035,345	964,346	947,168
Net cash (used in) provided by operating activities of discontinued operations	0	(56,070)	168,662
Net cash provided by operating activities	1,035,345	908,276	1,115,830
Investing Activities
Purchases of available-for-sale investments	(466,687)	(1,155,659)	(2,238,784)
Proceeds from sales of available-for-sale investments	455,417	775,135	1,294,636
Proceeds from maturities of available-for-sale investments	468,145	466,900	632,517
Purchases of property and equipment	(69,354)	(80,901)	(85,035)
Cash paid for acquisitions, net of cash acquired	(248,929)	(60,449)	(13,242)
Cash paid for licensing agreements and product related intangible assets	(3,210)	(7,379)	(25,940)
Other	(3,202)	2,323	1,181
Net cash provided by (used in) investing activities of continuing operations	132,180	(60,030)	(434,667)
Net cash used in investing activities of discontinued operations	0	(3,891)	(49,537)
Net cash provided by (used in) investing activities	132,180	(63,921)	(484,204)
Financing Activities
Proceeds from issuance of common stock under stock-based compensation plans	164	2,114	41,247
Proceeds from revolving credit facility	0	165,000	0
Repayments on credit facility	0	(165,000)	0
Proceeds from 2027 notes, net of issuance costs	0	741,039	0
Repayment of acquired debt	(5,674)	(4,000)	0
Excess tax benefit from stock-based compensation			16,049
Stock repurchases, net	(1,261,153)	(1,174,957)	(28,689)
Accelerated stock repurchase program	0	(150,000)	0
Cash paid for tax withholding on vested stock awards	(71,593)	(80,040)	(66,638)
Common stock cash dividends paid	(46,799)	0	0
Repayment on convertible debt	(272,986)	0	0
Transfer of cash to GoTo Business resulting from the separation	0	(28,523)	0
Net cash used in financing activities	(1,658,041)	(694,367)	(38,031)
Effect of exchange rate changes on cash and cash equivalents	(5,848)	8,186	(5,157)
Change in cash and cash equivalents	(496,364)	158,174	588,438
Cash and cash equivalents at beginning of period, including cash of discontinued operations of $0, $120,861 and $57,762, respectively	1,115,130	956,956	368,518
Cash and cash equivalents at end of period	618,766	1,115,130	956,956
Less cash of discontinued operations	0	0	(120,861)
Cash and cash equivalents at end of period	618,766	1,115,130	836,095
Supplemental Cash Flow Information
Cash paid for income taxes	110,808	61,126	64,361
Cash paid for interest	$ 41,834	$ 8,764	$ 7,847