CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Operating activities
Net income (loss)	$ (47,874)	$ (24,221)
Less: Income (loss) from discontinued operations, net of tax	0	1,751
Income (loss) from continuing operations	(47,874)	(22,470)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization of property, equipment and software	76,984	86,355
Amortization of acquired intangible assets	10,316	17,622
Stock-based compensation	50,670	60,318
Gain on sale of intangible assets	0	(17,149)
Gain on sale of investment	0	(7,624)
Impairments of investments	10,156	0
Deferred income taxes	(6,575)	845
(Gain) loss from changes in fair value of investments	8,312	5,100
Amortization of debt discount on convertible senior notes	8,822	7,964
Change in assets and liabilities, net of acquisitions and dispositions:
Accounts receivable	20,217	787
Prepaid expenses and other current assets	(2,695)	(3,114)
Accounts payable	(16,034)	(5,616)
Accrued merchant and supplier payables	(214,748)	(197,836)
Accrued expenses and other current liabilities	(45,175)	(39,396)
Other, net	14,663	(21,490)
Net cash provided by (used in) operating activities from continuing operations	(132,961)	(135,704)
Net cash provided by (used in) operating activities from discontinued operations	0	(2,195)
Net cash provided by (used in) operating activities	(132,961)	(137,899)
Investing activities
Purchases of property and equipment and capitalized software	(53,611)	(43,716)
Proceeds from sale of intangible assets	1,500	18,333
Proceeds from sales and maturities of investments	8,594	16,561
Acquisition of business, net of acquired cash	(57,821)	0
Acquisitions of intangible assets and other investing activities	(17,147)	(750)
Net cash provided by (used in) investing activities from continuing operations	(118,485)	(9,572)
Net cash provided by (used in) investing activities from discontinued operations	0	(9,548)
Net cash provided by (used in) investing activities	(118,485)	(19,120)
Financing activities
Payments for purchases of treasury stock	0	(61,233)
Taxes paid related to net share settlements of stock-based compensation awards	(18,638)	(23,340)
Proceeds from stock option exercises and employee stock purchase plan	5,710	5,486
Distributions to noncontrolling interest holders	(9,316)	(8,974)
Payments of capital lease obligations	(25,289)	(25,298)
Payments of contingent consideration related to acquisitions	(1,815)	(7,790)
Other financing activities	0	(473)
Net cash provided by (used in) financing activities	(49,348)	(121,622)
Effect of exchange rate changes on cash, cash equivalents and restricted cash, including cash classified within current assets of discontinued operations	(9,287)	23,275
Net increase (decrease) in cash, cash equivalents and restricted cash, including cash classified within current assets of discontinued operations	(310,081)	(255,366)
Less: Net increase (decrease) in cash classified within current assets of discontinued operations	0	(28,866)
Net increase (decrease) in cash, cash equivalents and restricted cash	(310,081)	(226,500)
Cash, cash equivalents and restricted cash, beginning of period	885,481	874,906
Cash, cash equivalents and restricted cash, end of period	575,400	648,406
Non-cash investing and financing activities
Equipment acquired under capital lease obligations	13,789	17,892
Leasehold improvements funded by lessor	557	402
Increase (decrease) in liabilities related to purchases of property and equipment and capitalized software	699	396
Investments acquired in connection with business dispositions	0	2,022
Contingent consideration liability incurred in connection with acquisition of business	1,589	0
Financing obligation incurred in connection with acquisition of business	$ 8,604	$ 0