Commitments and Contingencies - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	0 Months Ended	3 Months Ended		3 Months Ended										3 Months Ended
	Aug. 07, 2012 Plaintiff	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 Sales and support office [Member] OptionPlan	Mar. 31, 2013 General office [Member]	Mar. 31, 2013 New York [Member]	Mar. 31, 2013 Office Leases [Member]	Mar. 31, 2012 Office Leases [Member]	Dec. 31, 2012 Office Leases [Member]	Mar. 31, 2013 Office Leases [Member] Accrued expenses [Member]	Dec. 31, 2012 Office Leases [Member] Accrued expenses [Member]	Mar. 31, 2013 Office Leases [Member] Other long-term liabilities [Member]	Dec. 31, 2012 Office Leases [Member] Other long-term liabilities [Member]	Mar. 31, 2013 Headquarters space [Member] OptionPlan	Mar. 31, 2013 Third-Party Hosting Agreements [Member] Vendor	Mar. 31, 2012 Third-Party Hosting Agreements [Member]	Dec. 31, 2012 Third-Party Hosting Agreements [Member]	Mar. 31, 2013 Third-Party Hosting Agreements [Member] Other long-term liabilities [Member]	Dec. 31, 2012 Third-Party Hosting Agreements [Member] Other long-term liabilities [Member]
Operating Leased Assets [Line Items]
Lease expiration date														Sep. 22, 2022
Time period for extension option				3 years										10 years
Number of extension option				3										1
Expiration of lease agreement		Various dates through mid-2017		April 2019	Various dates through 2017	October 2018
Prepaid rent							$ 1,696		$ 1,725						$ 1,024		$ 1,120
Prepaid expenses and other current assets		9,644	6,513				456		302						253		259
Other assets							1,240		1,423						771		861
Accrued rent balance							2,242		2,154
Accrued rent balance included in accrued expenses										323	282
Accrued rent balance included in other long-term liabilities												1,919	1,872					150	138
Rent expense							1,970	1,513							1,007	906
Additional increase in contractual obligation for 2013		161
Additional increase in contractual obligation for 2014		656
Additional increase in contractual obligation for 2015		676
Additional increase in contractual obligation for 2016		696
Additional increase in contractual obligation for 2017		717
Additional increase in contractual obligation for 2018		614
Number of vendors provide for related services															2
Amount of contractual commitments with various vendors		22,502
Letter of credit for the benefit of the landlord		1,300	750
Cash balance to secure the letter of credit		1,300	750
Contingent consideration for revenue		22,500
Accrual for contingency		0	0
Number of Plaintiffs	2
Loss contingency accrual		$ 820