Summary Of Operations And Significant Accounting Policies (Narrative) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 segment	Dec. 31, 2011	Dec. 31, 2010
Organization Consolidation And Summary Of Significant Accounting Policies [Line Items]
Propert, plant and equipment, useful life	3 years
Depreciation	$ 7,329	$ 6,563	$ 5,791
Typical service agreements	12 months
Fees and related labor costs, recognition period (current estimate of term of customer relationship)	48 months
Advertising costs	6,374	6,310	6,132
Weighted average fair value of stock options granted	$ 8.20	$ 6.47	$ 3.89
Dividend yield	0.00%	0.00%	0.00%
Expected life (in years)	5 years	5 years	5 years
Effect of option to purchase share of common stock on diluted net income per share	4,865,957	5,235,305	5,294,867
Weighted average exercise price of options	$ 6.80	$ 4.94	$ 3.61
Shares excluded from computation of earnings per share	4,975,525	3,608,110	3,524,395
Number of operating segments	2
Capitalized computer software	2,437	1,086
Foreign currency translation adjustments	19	35	127
Aggregate amortization expense for intangible assets	580	1,029	1,486
Estimated amortization expense in 2013	4,339
Estimated amortization expense in 2014	4,117
Estimated amortization expense in 2015	3,755
Estimated amortization expense in 2016	3,314
Estimated amortization expense in 2017	43
Estimated amortization expenses thereafter	$ 113
Minimum [Member]
Organization Consolidation And Summary Of Significant Accounting Policies [Line Items]
Propert, plant and equipment, useful life	3 years
Typical service agreements termination notice period	30 days
Maximum [Member]
Organization Consolidation And Summary Of Significant Accounting Policies [Line Items]
Propert, plant and equipment, useful life	5 years
Typical service agreements termination notice period	90 days
Accounts Receivable [Member]
Organization Consolidation And Summary Of Significant Accounting Policies [Line Items]
Percentage of accounts receivable accounted for one customer	15.00%	18.00%