Consolidated Statements of Cash Flows - USD ($) $ in Thousands		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016
Operating activities
Net loss		$ (27,161)	$ (97,327)
Less: Income (loss) from discontinued operations		(889)	(5,020)
Loss from continuing operations		(26,272)	(92,307)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Depreciation, Depletion and Amortization		57,163	59,096
Amortization of acquired intangible assets		11,583	9,235
Share-based Compensation		41,141	66,603
Restructuring Costs and Asset Impairment Charges		0	45
Gain (Loss) on Disposition of Business		0	(9,339)
Deferred income taxes		759	(5,148)
Gain from changes in fair value of contingent consideration	[1]	48	4,292
Fair Value, Option, Changes in Fair Value, Gain (Loss)		1,145	5,707
Amortization of Debt Discount (Premium)		5,242	2,396
Change in assets and liabilities, net of acquisitions:
Restricted cash		548	(695)
Accounts receivable		16,229	(500)
Prepaid expenses and other current assets		(11,139)	(36,900)
Accounts payable		(10,723)	(5,693)
Accrued merchant and supplier payables		(182,954)	(120,629)
Accrued expenses and other current liabilities		(41,491)	4,955
Other, net		(18,207)	(6,904)
Net cash provided by (used in) operating activities from continuing operations		(156,928)	(125,786)
Net cash used in operating activities from discontinued operations		(2,195)	(4,949)
Net cash provided by (used in) operating activities		(159,123)	(130,735)
Investing activities
Purchases of property and equipment and capitalized software		(29,461)	(36,351)
Cash Divested from Deconsolidation		0	(352)
Proceeds from Maturities, Prepayments and Calls of Available-for-sale Securities		1,843	0
Payments to Acquire Businesses, Net of Cash Acquired		0	(940)
Acquisitions of intangible assets and other investing activities		(184)	(1,992)
Net cash used in investing activities from continuing operations		(27,802)	(39,635)
Net cash used in investing activities from discontinued operations		(9,548)	4
Net cash used in investing activities		(37,350)	(39,631)
Financing activities
Proceeds from Issuance of Senior Long-term Debt		0	250,000
Payments of Debt Issuance Costs		0	(8,097)
Purchase of Convertible Note Hedges		0	(59,163)
Proceeds from Issuance of Warrants		0	35,495
Payments for purchases of treasury stock		(51,513)	(90,449)
Taxes paid related to net share settlements of stock-based compensation awards		(15,356)	(16,535)
Proceeds from stock option exercises and employee stock purchase plan		2,477	2,047
Partnership distribution payments to noncontrolling interest holders		(6,426)	(7,127)
Payment of Contingent Consideration		(5,689)	(285)
Payments of capital lease obligations		(16,670)	(14,676)
Proceeds from (Payments for) Other Financing Activities		(473)	0
Net cash used in financing activities		(93,650)	91,210
Effect of exchange rate changes on cash and cash equivalents		16,830	5,926
Net decrease in cash and cash equivalents, including cash classified within current assets held for sale		(273,293)	(73,230)
Less: Increase in cash and cash equivalents classified within current assets held for sale		(28,866)	1,402
Net decrease in cash and cash equivalents		(244,427)	(74,632)
Cash and cash equivalents, beginning of period		862,977	824,307
Cash and cash equivalents, end of period		618,550	749,675
Non-cash investing and financing activities
Equipment acquired under capital lease obligations		16,509	10,081
Payments for Tenant Improvements		402	4,990
Liability for Purchases of Treasury Stock		561	1,592
Accounts payable and accrued expenses related to purchases of property and equipment and capitalized software		(539)	(3,860)
Continuing Operations [Member]
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Share-based Compensation		41,100	66,600
Discontinued Operations [Member]
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Amortization of acquired intangible assets		0	0
Share-based Compensation		200	1,700
Investment Type [Member]
Non-cash investing and financing activities
Noncash or Part Noncash Acquisition, Investments Acquired		2,022	8,323
GroupMax [Member]
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Fair Value, Option, Changes in Fair Value, Gain (Loss)		$ 3,400	$ 4,300

[1] Changes in the fair value of contingent consideration liabilities are classified within "Acquisition-related expense (benefit), net" on the condensed consolidated statements of operations.