Supplemental Consolidated Balance Sheet and Statement of Operations Information (Details) - USD ($) $ in Thousands		3 Months Ended			6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016		Jun. 30, 2017	Jun. 30, 2016		Dec. 31, 2016
Interest and Other Income [Abstract]
Interest income		$ 659	$ 376		$ 1,261	$ 709
Interest expense		(4,948)	(5,232)		(10,267)	(6,074)
Fair Value, Option, Changes in Fair Value, Gain (Loss)		(1,448)	(4,607)		(1,145)	(5,707)
Foreign exchange losses, net		10,826	(1,636)	[1]	10,877	4,007	[1]
Other Noncash Income (Expense)		789	(154)		550	(1,570)
Other expense, net		5,878	(11,253)		1,276	(8,635)
Reclassification of amount included in net income (loss) from continuing operations			$ (1,800)			$ (300)
Prepaid Expense and Other Assets, Current [Abstract]
Finished goods inventories		24,346			24,346			$ 31,042
Prepaid expenses		49,149			49,149			34,132
Income taxes receivable		12,093			12,093			11,495
VAT receivable		10,910			10,910			5,965
Other		11,029			11,029			11,807
Total prepaid expenses and other current assets		107,527			107,527			94,441
Merchant and Supplier Payables [Abstract]
Accrued merchant payables		429,925			429,925			428,187
Accrued supplier payables	[2]	176,095			176,095			342,805
Total accrued merchant and supplier payables		606,020			606,020			770,992
Accrued Expenses [Abstract]
Refunds reserve		26,237			26,237			33,104
Payroll and benefits		52,781			52,781			55,590
Customer credits		43,399			43,399			42,003
Restructuring Reserve, Current		5,511			5,511			16,395
Taxes Payable, Current		12,681			12,681			10,847
Deferred revenue		33,720			33,720			35,890
Capital lease obligations		29,497			29,497			28,889
Other		125,172			125,172			143,738
Total accrued expenses		328,998			328,998			366,456
Liabilities, Noncurrent [Abstract]
Long-term tax liabilities		45,857			45,857			41,611
Capital lease obligations		19,820			19,820			19,719
Other		36,301			36,301			38,298
Total other non-current liabilities		101,978			101,978			$ 99,628
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Beginning Balance, Equity					265,062
Other comprehensive income (loss) before reclassification adjustments					(8,033)
Reclassification adjustments included in net income (loss)					(15,661)
Other comprehensive income (loss)					(23,694)
Ending Balance, Equity		185,982			185,982
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					(7,320)
Reclassification adjustments included in net income (loss)					(14,905)
Other comprehensive income (loss)					(22,225)
Ending Balance, Equity		36,024			36,024
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					(713)
Reclassification adjustments included in net income (loss)					(1,341)
Other comprehensive income (loss)					(2,054)
Ending Balance, Equity		(1,666)			(1,666)
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
Ending Balance, Equity		$ 34,358			$ 34,358

[1] Foreign currency gains (losses), net for the three and six months ended June 30, 2016 includes a $1.8 million and $0.3 million, respectively, of cumulative translation gains that were 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.