Balance Sheet Detail (Details) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Summary of prepaid expenses and other assets
Prepaid commission	$ 7,471,000	$ 5,729,000
Prepaid royalty	1,121,000	803,000
Prepaid contract expense	8,858,000	6,043,000
Tenant improvement allowance		182,000
Other	6,210,000	5,107,000
Total prepaid expenses and other assets	23,660,000	17,864,000
Summary of property and equipment
Property and equipment, gross	97,454,000	88,369,000
Accumulated depreciation	(55,153,000)	(46,845,000)
Property and equipment, net	42,301,000	41,524,000
Depreciation	11,000,000	10,000,000	9,400,000
Costs related to development of internal use software capitalized during the period	1,300,000	700,000	2,000,000
Computer equipment - hardware
Summary of property and equipment
Property and equipment, gross	27,359,000	23,726,000
Computer equipment - software
Summary of property and equipment
Property and equipment, gross	25,092,000	23,783,000
Leasehold improvements
Summary of property and equipment
Property and equipment, gross	34,371,000	31,678,000
Furniture and fixtures
Summary of property and equipment
Property and equipment, gross	9,001,000	7,866,000
Construction in process
Summary of property and equipment
Property and equipment, gross	$ 1,631,000	$ 1,316,000