Summary of Significant Accounting Policies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Long-Lived Assets
Cost	$ 51,500	$ 45,101
Accumulated Depreciation/ Amortization	$ (42,479)	(39,260)
Furniture and fixtures
Long-Lived Assets
Estimated useful lives	5 years
Cost	$ 1,904	1,411
Accumulated Depreciation/ Amortization	$ (1,005)	(713)
Equipment, Computer Hardware And Purchased Software [Member] | Minimum
Long-Lived Assets
Estimated useful lives	2 years
Equipment, Computer Hardware And Purchased Software [Member] | Maximum
Long-Lived Assets
Estimated useful lives	3 years
Office equipment
Long-Lived Assets
Cost	$ 600	472
Accumulated Depreciation/ Amortization	(345)	(178)
Computer hardware
Long-Lived Assets
Cost	4,526	3,258
Accumulated Depreciation/ Amortization	(3,254)	(2,523)
Purchased software
Long-Lived Assets
Cost	34,155	32,352
Accumulated Depreciation/ Amortization	$ (31,825)	(31,110)
Costs of internal-use software
Long-Lived Assets
Estimated useful lives	3 years
Cost	$ 6,479	5,868
Accumulated Depreciation/ Amortization	(5,298)	(4,320)
Leasehold improvements
Long-Lived Assets
Cost	3,836	1,740
Accumulated Depreciation/ Amortization	$ (752)	$ (416)