Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net income (loss)		$ 4,698	$ (4,381)	[1]
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization		16,909	16,279	[1]
Stock-based compensation expense		31,482	33,758	[1]
(Gain) loss from foreign currency, sales of investments, assets and other, net		1,491	(184)	[1]
(Accretion) and amortization on marketable debt securities, net		(1,300)
Change in deferred income taxes and other		1,273	2,268	[1]
Changes in operating assets and liabilities:
Accounts receivable, net		14,009	(7,968)	[1]
Other assets		(7,223)	(2,594)	[1]
Accounts payable		(16,261)	(8,341)	[1]
Deferred revenue		28,126	13,021	[1]
Income tax payable		(5,042)	2,749	[1]
Other liabilities		(30,974)	(11,698)	[1]
Net cash provided by (used in) operating activities		37,188	32,909	[1]
Cash flows from investing activities:
Purchases of short-term investments		(184,089)
Maturities of short-term investments		302,000
Sales of short-term investments		9,999
Acquisition of property and equipment		(3,679)	(4,141)	[1]
Proceeds from sale of property and equipment		28	148	[1]
Business acquisitions, net of cash acquired and restricted cash held in escrow		(222,075)	(27,581)	[1]
Release of restricted cash escrow from business combinations		(22,800)
Other investing activities, net		97	(7,225)	[1]
Net cash provided by (used in) investing activities		(120,519)	(38,799)	[1]
Cash flows from financing activities:
Taxes paid related to net share settlement of stockholders' equity awards		(13,972)	(9,423)	[1]
Repurchases of common stock		(65,418)	(96,924)	[1]
Proceeds from issuance of common stock		4,158	4,017	[1]
Acquisition-related contingent consideration payment	[1]		(5,115)
Net cash provided by (used in) financing activities		(75,232)	(107,445)	[1]
Effect of exchange rate changes on cash, cash equivalents and restricted cash		(1,931)	2,026	[1]
Net change in cash, cash equivalents and restricted cash		(160,494)	(111,309)	[1]
Cash, cash equivalents and restricted cash, beginning of period		405,677	861,716	[1]
Cash, cash equivalents and restricted cash, end of period		245,183	750,407	[1]
Supplemental cash flow information:
Income taxes paid		$ 10,261	$ 434	[1]

[1] Prior period amounts retrospectively adjusted to reflect the adoption of ASU 2016-18, “Statement of Cash Flows (Topic 230): Restricted Cash”. Refer to Note 1 – “Overview and Summary of Significant Accounting Policies” in the notes to the interim consolidated financial statements for further discussion on the adoption.