Income Taxes - Additional Information (Detail) - USD ($)	11 Months Ended	12 Months Ended
	Dec. 31, 2017	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Income Taxes [Line Items]
Statutory tax rate	35.00%	21.00%	33.80%	34.00%
Increase in deferred tax assets corresponding decrease to income tax expense		$ 83,000,000
Decrease in long term tax liability corresponding decrease to income tax expense		170,000,000
Decrease in income tax expense		252,000,000
Deferred tax liabilities, not recognized		10,100,000
Cumulative undistributed earnings of foreign subsidiaries		67,200,000
Gross deferred tax assets, net of deferred tax liabilities before valuation allowance		21,800,000	$ 20,800,000
Deferred tax assets		10,799,000	3,979,000
Valuation allowance		12,526,000	18,538,000
Unrecognized tax benefits		37,531,000	34,117,000	$ 37,977,000	$ 30,211,000
Unrecognized tax benefits that would impact effective tax rate		31,600,000
Income tax liabilities considered as other long term liabilities		6,300,000	5,200,000
Interest expense and penalties related to uncertain tax positions		263,000	37,000
Noncurrent liabilities related to interest and penalties for uncertain tax positions		403,000	$ 139,000
Long term income taxes payable, including estimated interest and penalties		$ 6,700,000
U.S. federal tax authorities [Member] | Earliest tax year [Member]
Income Taxes [Line Items]
Income tax examination, year		2013
U.S. federal tax authorities [Member] | Latest tax year [Member]
Income Taxes [Line Items]
Income tax examination, year		2018
U.S. state tax authorities [Member] | Earliest tax year [Member]
Income Taxes [Line Items]
Income tax examination, year		2009
U.S. state tax authorities [Member] | Latest tax year [Member]
Income Taxes [Line Items]
Income tax examination, year		2018
Foreign tax authorities [Member] | Earliest tax year [Member]
Income Taxes [Line Items]
Income tax examination, year		2013
Foreign tax authorities [Member] | Latest tax year [Member]
Income Taxes [Line Items]
Income tax examination, year		2018
Federal [Member]
Income Taxes [Line Items]
Research and development credit carryforwards		$ 16,900,000
Federal credits begin to expire in fiscal year		2033
California state [Member]
Income Taxes [Line Items]
Research and development credit carryforwards		$ 20,000,000
Research and Development [Member] | Federal [Member]
Income Taxes [Line Items]
Valuation allowance related to credit carryforwards		8,000,000
Deferred tax assets		$ 8,000,000