Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jun. 30, 2016
Income Taxes [Line Items]
Tax charge (benefit)		$ (1,200)	$ 27,500
Earnings deemed repatriated, tax expense		17,000
Minimum tax on foreign earnings	$ 4,700
Estimated charges related to remeasurement of U.S. deferred tax assets and liabilities		(343)	10,450	$ 0
Estimated charges related to deemed repatriation transition tax, gross			27,000
Foreign tax credits			10,000
Unrecognized tax benefits that would affect the effective tax rate if recognized	31,700	31,700	33,900	32,000
Amounts netted against related deferred tax assets	400	400	400	1,100
Gross unrecognized tax benefits decrease in next 12 months	6,500	6,500
Offset to deferred tax assets for unrecognized tax benefits	16,500	16,500
Noncurrent income tax payable	15,200	15,200
Accrued interest and penalties related to unrecognized tax benefits	900	900	$ 700	$ 500
Deferred tax assets related to excess tax benefits for federal research and development income tax credits					$ 2,200
Deferred tax assets for tax benefit on cumulative effect adjustment associated with change in accounting					$ 600
Federal
Income Taxes [Line Items]
Loss carryforwards	11,400	11,400
Credit carryforwards	37,700	37,700
State
Income Taxes [Line Items]
Loss carryforwards	47,600	47,600
Credit carryforwards	39,600	39,600
Equity component
Income Taxes [Line Items]
Deferred tax liability	$ 6,619	$ 6,619