Summary of Significant Accounting Policies - Comprehensive (Loss) Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended													12 Months Ended
	Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011		Jun. 30, 2011	Mar. 31, 2011		Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Accounting Policies [Abstract]
Net (loss) income	$ (973)	[1]	$ (608)	[2]	$ (399)	[3]	$ (1,438)	$ (6,527)	$ 686	[4]	$ 3,393	$ (1,125)	[5]	$ (3,419)	$ (3,573)	$ 3,803
Change in unrealized gain (loss) on available-for-sale securities, net of tax effect														1	(1)	0
Comprehensive (loss) income														$ (3,418)	$ (3,574)	$ 3,803

[1] During the fourth quarter of 2012, the Company recorded correcting entries to reduce revenue by $87 thousand for the correction of immaterial errors in deferred revenue balances, to reduce stock-based compensation expense by $106 thousand for the correction of immaterial errors in additional paid-in capital, to increase royalty expenses by $39 thousand for the correction of immaterial errors in accrued royalties and to increase sales tax expense by $106 thousand for the correction of immaterial errors in other assets.

[2] During the third quarter of 2012, the Company recorded a correcting entry to reduce stock-based compensation expense by $32 thousand for the correction of immaterial errors in additional paid-in capital for the three months ended September 30, 2012.

[3] During the second quarter of 2012, the Company recorded correcting entries to increase operating expenses by $51 thousand for the correction of immaterial errors in accrued expenses in the three months ended June 30, 2012.

[4] During the third quarter of 2011, the Company recorded correcting entries to increase royalty and consulting expenses by $127 thousand for the correction of immaterial errors in capitalization of costs related to internal use software.

[5] During the first quarter of 2011, the Company recorded correcting entries to increase consulting expenses by $36 thousand for the correction of immaterial errors in accrued expenses and to increase revenue by $88 thousand for the correction of immaterial errors in deferred revenue.