Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Intangible assets
Gross carrying value	$ 42,290		$ 42,290		$ 42,290
Accumulated amortization	(16,409)		(16,409)		(14,341)
Net carrying value	25,881		25,881		27,949
Amortization expense	1,000	$ 1,100	2,100	$ 2,200
Acquired technology and domain name
Intangible assets
Gross carrying value	31,090		31,090		31,090
Accumulated amortization	(12,312)		(12,312)		(10,788)
Net carrying value	18,778		18,778		20,302
Customer relationships
Intangible assets
Gross carrying value	6,300		6,300		6,300
Accumulated amortization	(2,872)		(2,872)		(2,491)
Net carrying value	3,428		3,428		3,809
Trade names
Intangible assets
Gross carrying value	4,900		4,900		4,900
Accumulated amortization	(1,225)		(1,225)		(1,062)
Net carrying value	$ 3,675		$ 3,675		$ 3,838