Supplemental Consolidated Balance Sheet and Statement of Operations Information (Details) - USD ($) $ in Thousands		3 Months Ended			9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016		Sep. 30, 2017	Sep. 30, 2016		Dec. 31, 2016
Interest and Other Income [Abstract]
Interest income		$ 894	$ 549		$ 2,155	$ 1,258
Interest expense		(5,156)	(5,882)		(15,423)	(11,956)
Fair Value, Option, Changes in Fair Value, Gain (Loss)		(3,955)	(1,594)		(5,100)	(7,301)
Cost-method Investments, Realized Gain (Loss), Excluding Other than Temporary Impairments		7,624	0		7,624	0
Foreign exchange losses, net		8,186	(504)	[1]	19,063	3,503	[1]
Other Noncash Income (Expense)		(47)	(486)		503	(2,056)
Other expense, net		7,546	$ (7,917)		8,822	(16,552)
Reclassification of amount included in net income (loss) from continuing operations						$ (200)
Prepaid Expense and Other Assets, Current [Abstract]
Finished goods inventories		25,205			25,205			$ 31,042
Prepaid expenses		44,936			44,936			34,132
Income taxes receivable		12,933			12,933			11,495
VAT receivable		8,037			8,037			5,965
Other		8,744			8,744			11,807
Total prepaid expenses and other current assets		99,855			99,855			94,441
Merchant and Supplier Payables [Abstract]
Accrued merchant payables		421,334			421,334			428,187
Accrued supplier payables	[2]	176,917			176,917			342,805
Total accrued merchant and supplier payables		598,251			598,251			770,992
Accrued Expenses [Abstract]
Refunds reserve		25,469			25,469			33,104
Payroll and benefits		58,803			58,803			55,590
Customer credits		39,540			39,540			42,003
Restructuring Reserve, Current		9,844			9,844			16,395
Taxes Payable, Current		13,050			13,050			10,847
Deferred revenue		30,685			30,685			35,890
Capital lease obligations		25,294			25,294			28,889
Other		121,868			121,868			143,738
Total accrued expenses		324,553			324,553			366,456
Liabilities, Noncurrent [Abstract]
Long-term tax liabilities		47,995			47,995			41,611
Capital lease obligations		17,062			17,062			19,719
Other		37,329			37,329			38,298
Total other non-current liabilities		102,386			102,386			$ 99,628
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Beginning Balance, Equity					265,062
Ending Balance, Equity		188,066			188,066
Foreign Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Beginning Balance, Equity					58,249
Other comprehensive income (loss) before reclassification adjustments					(12,354)
Reclassification adjustments included in net income (loss)					(14,905)
Other comprehensive income (loss)					(27,259)
Ending Balance, Equity		30,990			30,990
Unrealized Gain (Loss) On Available-For-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Beginning Balance, Equity					388
Other comprehensive income (loss) before reclassification adjustments					(938)
Reclassification adjustments included in net income (loss)					(1,341)
Other comprehensive income (loss)					(2,279)
Ending Balance, Equity		(1,891)			(1,891)
Pension Adjustment [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Beginning Balance, Equity					(585)
Other comprehensive income (loss) before reclassification adjustments					0
Reclassification adjustments included in net income (loss)					585
Other comprehensive income (loss)					585
Ending Balance, Equity		0			0
AOCI Including Portion Attributable to Noncontrolling Interest [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Beginning Balance, Equity					58,052
Other comprehensive income (loss) before reclassification adjustments					(13,292)
Reclassification adjustments included in net income (loss)					(15,661)
Other comprehensive income (loss)					(28,953)
Ending Balance, Equity		$ 29,099			$ 29,099

[1] Foreign currency gains (losses), net includes a $0.2 million cumulative translation gain for the nine months ended September 30, 2016 that was reclassified to earnings as a result of the Company's exit from certain countries as part of its restructuring plan. Refer to Note 9, Restructuring, for additional information.

[2] Amounts include payables to suppliers of inventories and providers of shipping and fulfillment services.