Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 83,631	$ 45,457
Adjustments to reconcile net income to net cash from operating activities:
Depreciation	16,189	7,949
Provision for doubtful accounts	741	338
Deferred taxes	2,048	(2,162)
Amortization of intangible assets	45,598	25,118
Stock-based compensation	36,445	23,913
Deferred rent	3,975	130
Amortization of deferred loan costs	588	349
Other	(732)	(823)
Change in assets and liabilities, net of the effects of business acquisitions:
Accounts receivable	(17,969)	(15,903)
Income taxes receivable	(5,533)	3,795
Prepaid expenses and other assets	(15,455)	4,193
Restaurant food liability	1,608	4,591
Accounts payable	5,265	2,965
Accrued payroll	5,311	1,575
Other accruals	3,752	6,351
Net cash provided by operating activities	165,462	107,836
CASH FLOWS FROM INVESTING ACTIVITIES
Acquisitions of businesses, net of cash acquired	(366,856)	(51,859)
Purchases of investments	(47,642)	(145,667)
Proceeds from maturity of investments	54,916	164,733
Capitalized website and development costs	(21,471)	(15,281)
Purchases of property and equipment	(31,984)	(12,549)
Acquisition of other intangible assets		(25,147)
Other cash flows from investing activities	38	589
Net cash used in investing activities	(412,999)	(85,181)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of common stock	200,000
Proceeds from borrowings under the Credit Agreement	175,000
Repayments of borrowings under the Credit Agreement	(52,344)
Proceeds from exercise of stock options	13,010	12,505
Taxes paid related to net settlement of stock-based compensation awards	(28,238)	(7,696)
Payments for debt issuance costs		(285)
Net cash provided by financing activities	307,428	4,524
Net change in cash, cash equivalents, and restricted cash	59,891	27,179
Effect of exchange rates on cash, cash equivalents and restricted cash	(406)	709
Cash, cash equivalents, and restricted cash at beginning of year	238,239	242,214
Cash, cash equivalents, and restricted cash at end of the period	297,724	270,102
SUPPLEMENTAL DISCLOSURE OF NON-CASH ITEMS
Cash paid for income taxes	7,508	16,340
Capitalized property, equipment and website and development costs in accounts payable at period end	4,069	1,048
Net working capital adjustment receivable	530	887
Fair value of equity awards assumed on acquisition	2,594
RECONCILIATION OF CASH, CASH EQUIVALENTS, AND RESTRICTED CASH
Cash and cash equivalents	$ 294,550	265,958
Restricted cash included in prepaid expenses and other current assets		$ 1,500
Restricted Cash, Current, Asset, Statement of Financial Position [Extensible List]	us-gaap:PrepaidExpenseAndOtherAssetsCurrent	us-gaap:PrepaidExpenseAndOtherAssetsCurrent
Restricted cash included in other assets	$ 3,174	$ 2,644
Restricted Cash, Noncurrent, Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsNoncurrent	us-gaap:OtherAssetsNoncurrent
Total cash, cash equivalents, and restricted cash	$ 297,724	$ 270,102