Revision of Prior Period Financial Statements - Revised Consolidated Balance Sheet (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Current Assets:
Prepaid expenses and other current assets	$ 20,762	$ 18,904
Total current assets	266,389	336,623
Other assets	10,167	9,248
Total assets	402,202	488,015
Current Liabilities:
Deferred revenue	152,903	150,495
Total current liabilities	187,398	181,345
Non-current liabilities	10,142	9,463
Total liabilities	197,540	190,808
Retained earnings	118,415	117,785
Total stockholders' equity	204,662	297,207	290,150	272,341
Total liabilities and stockholders' equity	402,202	488,015
As Previously Reported [Member]
Current Assets:
Prepaid expenses and other current assets		18,846
Total current assets		336,565
Other assets		9,123
Total assets		487,832
Current Liabilities:
Deferred revenue		150,479
Total current liabilities		181,329
Non-current liabilities		9,433
Total liabilities		190,762
Retained earnings		117,648
Total stockholders' equity		297,070
Total liabilities and stockholders' equity		487,832
Adjustments [Member]
Current Assets:
Prepaid expenses and other current assets		58
Total current assets		58
Other assets		125
Total assets		183
Current Liabilities:
Deferred revenue		16
Total current liabilities		16
Non-current liabilities		30
Total liabilities		46
Retained earnings		137
Total stockholders' equity		137
Total liabilities and stockholders' equity		183
As Revised [Member]
Current Assets:
Prepaid expenses and other current assets		18,904
Total current assets		336,623
Other assets		9,248
Total assets		488,015
Current Liabilities:
Deferred revenue		150,495
Total current liabilities		181,345
Non-current liabilities		9,463
Total liabilities		190,808
Retained earnings		117,785
Total stockholders' equity		297,207
Total liabilities and stockholders' equity		$ 488,015