Income Taxes - Additional Information (Detail) - USD ($)	1 Months Ended	11 Months Ended	12 Months Ended
	Jan. 31, 2018	Dec. 31, 2017	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015
Income Taxes [Line Items]
Statutory tax rate		35.00%	33.80%	34.00%	34.00%
Decrease of deferred tax assets and corresponding increase in deferred tax expense			$ 1,900,000
Deferred tax liabilities, not recognized	$ 6,200,000		6,200,000
Cumulative undistributed earnings of foreign subsidiaries	51,000,000		51,000,000
Gross deferred tax assets, net of deferred tax liabilities before valuation allowance	20,800,000		20,800,000	$ 19,500,000
Valuation allowance	18,538,000		18,538,000	15,061,000
Unrecognized tax benefits	34,117,000		34,117,000	37,977,000	$ 30,211,000	$ 4,671,000
Unrecognized tax benefits that would impact effective tax rate	22,500,000		22,500,000
Reductions for tax positions in prior years			11,313,000	0	$ 37,000
Income tax liabilities considered as other long term liabilities	5,200,000		5,200,000	1,800,000
Benefit from interest accruals, reserve released due to the lapse of statute of limitations				64,000
Interest expense and penalties related to uncertain tax positions			37,000
Noncurrent liabilities related to interest and penalties for uncertain tax positions	139,000		139,000	$ 103,000
Long term income taxes payable, including estimated interest and penalties	5,400,000		$ 5,400,000
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			2017
U.S. state tax authorities [Member] | Earliest tax year [Member]
Income Taxes [Line Items]
Income tax examination, year			2008
U.S. state tax authorities [Member] | Latest tax year [Member]
Income Taxes [Line Items]
Income tax examination, year			2017
Foreign tax authorities [Member] | Earliest tax year [Member]
Income Taxes [Line Items]
Income tax examination, year			2012
Foreign tax authorities [Member] | Latest tax year [Member]
Income Taxes [Line Items]
Income tax examination, year			2017
Federal [Member]
Income Taxes [Line Items]
Research and development credit carryforwards	13,800,000		$ 13,800,000
Federal credits begin to expire in fiscal year			2033
California state [Member]
Income Taxes [Line Items]
Research and development credit carryforwards	$ 17,100,000		$ 17,100,000
Scenario, Plan [Member]
Income Taxes [Line Items]
Statutory tax rate	21.00%		21.00%