Recent Accounting Standards - Line Items Adjusted in Consolidated Statement of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Net income	$ 12,167	$ 9,700	$ 20,394	$ (7,906)	$ 3,301	$ 12,699	$ 4,828	$ 1,673	$ 34,355	$ 22,501	$ 18,195
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization									16,699	3,701	15,532
Deferred taxes									(2,614)	(8,274)	(3,605)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets									6,415	(6,561)	(4,739)
Deposits and other assets									761	(1,201)	3,029
Accrued compensation and employee benefits									(2,658)	5,116	(6,209)
Deferred revenue and advance payments									$ 20,836	$ (22,126)	(589)
As Reported | ASU 2014-09
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Net income											17,643
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization											12,572
Deferred taxes											(2,011)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets											(4,279)
Deposits and other assets											2,981
Accrued compensation and employee benefits											(3,683)
Deferred revenue and advance payments											(1,609)
Effect of the Adoption | ASU 2014-09
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Net income											552
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization											2,960
Deferred taxes											(1,594)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets											(460)
Deposits and other assets											48
Accrued compensation and employee benefits											(2,526)
Deferred revenue and advance payments											$ 1,020