Segment Information Revenue by Segment and Category (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Gross Profit		$ 309,425	$ 293,268	$ 946,943	$ 928,747
Third party and other		302,458	283,809	919,884	888,014
Direct		332,008	402,746	1,050,827	1,220,736
Total revenue		634,466	686,555	1,970,711	2,108,750
North America [Member]
Gross Profit		207,908	201,661	662,705	634,778
Third party and other		414,214	483,281	1,339,483	1,501,016
International [Member]
Gross Profit		101,517	91,607	284,238	293,969
Total revenue	[1]	220,252	203,274	631,228	607,734
Local [Member] | North America [Member]
Gross Profit		162,914	152,873	511,865	475,703
Third party and other		194,090	176,223	602,169	552,515
Local [Member] | International [Member]
Gross Profit		67,860	59,257	189,357	186,448
Third party and other		71,574	64,282	201,257	201,145
Travel [Member] | North America [Member]
Gross Profit		14,060	17,257	46,980	49,303
Third party and other		18,300	21,239	61,082	63,554
Travel [Member] | International [Member]
Gross Profit		8,922	12,378	28,954	34,104
Third party and other		9,801	13,524	31,599	37,615
Third party and other [Member] | Goods [Member] | North America [Member]
Gross Profit		3,205	1,509	7,719	5,201
Third party and other		4,323	1,964	10,139	6,318
Third party and other [Member] | Goods [Member] | International [Member]
Gross Profit		3,639	5,698	11,800	23,249
Third party and other		4,370	6,577	13,638	26,867
Direct [Member] | Goods [Member] | North America [Member]
Gross Profit		27,729	30,022	96,141	104,571
Direct		197,501	283,855	666,093	878,629
Direct [Member] | Goods [Member] | International [Member]
Gross Profit		21,096	14,274	54,127	50,168
Direct		134,507	118,891	$ 384,734	$ 342,107
Sales Revenue, Net [Member]
Concentration of risk, percentage				10.00%	0.00%
United States
Total revenue		410,500	476,300	$ 1,317,900	$ 1,477,700
UNITED KINGDOM
Total revenue		$ 82,200	$ 73,500	$ 222,100	$ 225,900

[1] North America includes revenue from the United States of $410.5 million and $476.3 million for the three months ended September 30, 2017 and 2016, respectively, and $1,317.9 million and $1,477.7 million for the nine months ended September 30, 2017 and 2016, respectively. International includes revenue from the United Kingdom of $82.2 million and $73.5 million for the three months ended September 30, 2017 and 2016, respectively, and $222.1 million and $225.9 million for the nine months ended September 30, 2017 and 2016, respectively. There were no other individual countries that represented more than 10% of consolidated total revenue for the three and nine months ended September 30, 2017 and 2016. In prior periods, revenue was attributed to individual countries based on the domicile of the legal entities within the Company's consolidated group that undertook those transactions. Beginning in the second quarter of 2017, the Company updated its attribution of revenue by country in the current period to be based on the location of the customer. Prior period revenue amounts by country have been retrospectively adjusted to reflect that change in attribution.