Revenue Recognition - Summary of Impact of Adopting the New Revenue Standard on Condensed Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2018	Jul. 01, 2018	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 87,639		$ 121,860	$ 64,051
Cash held for customers	5,382		2,753	$ 3,481
Marketable securities	8,477		10,012
Accounts receivable, net	62,902		74,305
Prepaid expenses and other current assets	30,205		19,781
Total current assets	194,605		228,711
Property and equipment, net	28,876		28,895
Goodwill	200,786		200,024
Intangible assets, net	160,136		161,785
Other assets	33,301		16,553
Total assets	617,704		635,968
Current liabilities:
Accounts payable	10,166		10,251
Accrued expenses and other current liabilities	29,038		34,994
Customer account liabilities	5,382		2,753
Deferred revenue	58,496		75,356
Total current liabilities	103,082		123,354
Borrowings under credit facility	110,000		150,000
Deferred revenue, non-current	16,693		23,371
Deferred income taxes	7,457		8,367
Other liabilities	19,627		19,944
Total liabilities	256,859		325,036
Stockholders' equity
Preferred Stock, $.001 par value
Common Stock, $.001 par value	46		45
Additional paid-in-capital	700,520		678,549
Accumulated other comprehensive loss	(35,704)		(30,633)
Treasury stock, at cost	(128,216)		(129,914)
Accumulated deficit	(175,801)		(207,115)
Total stockholders' equity	360,845		310,932
Total liabilities and stockholders' equity	617,704		$ 635,968
Accounting Standards Update 2014-09 [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Current assets:
Accounts receivable, net	1,576
Prepaid expenses and other current assets	(11,162)
Total current assets	(9,586)
Other assets	(14,931)
Total assets	(24,517)
Current liabilities:
Deferred revenue	2,071	$ 9,839
Total current liabilities	2,071
Deferred revenue, non-current	6,542
Deferred income taxes	1,619
Total liabilities	10,232
Stockholders' equity
Preferred Stock, $.001 par value
Accumulated other comprehensive loss	185
Accumulated deficit	(34,934)	$ 26,263
Total stockholders' equity	(34,749)
Total liabilities and stockholders' equity	(24,517)
Accounting Standards Update 2014-09 [Member] | Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Current assets:
Cash and cash equivalents	87,639
Cash held for customers	5,382
Marketable securities	8,477
Accounts receivable, net	64,478
Prepaid expenses and other current assets	19,043
Total current assets	185,019
Property and equipment, net	28,876
Goodwill	200,786
Intangible assets, net	160,136
Other assets	18,370
Total assets	593,187
Current liabilities:
Accounts payable	10,166
Accrued expenses and other current liabilities	29,038
Customer account liabilities	5,382
Deferred revenue	60,567
Total current liabilities	105,153
Borrowings under credit facility	110,000
Deferred revenue, non-current	23,235
Deferred income taxes	9,076
Other liabilities	19,627
Total liabilities	267,091
Stockholders' equity
Preferred Stock, $.001 par value
Common Stock, $.001 par value	46
Additional paid-in-capital	700,520
Accumulated other comprehensive loss	(35,519)
Treasury stock, at cost	(128,216)
Accumulated deficit	(210,735)
Total stockholders' equity	326,096
Total liabilities and stockholders' equity	$ 593,187