Description of Business and Basis of Presentation - Schedule of Decreases Cash Flows from Operating Activities Due to Adoption of ASU 2016-18 (Details) - USD ($) $ in Thousands		3 Months Ended			6 Months Ended			12 Months Ended
		Jul. 31, 2018	Jul. 31, 2017		Jul. 31, 2018	Jul. 31, 2017		Jan. 31, 2018	Jan. 31, 2017
Changes in operating assets and liabilities:
Prepaid expenses and other assets, current and noncurrent		$ 267	$ (3,402)	[1]	$ (4,933)	$ (5,943)	[1]
Net cash used in operating activities		(1,267)	(9,761)	[1]	17,173	(1,220)	[1]
Net decrease in cash, cash equivalents, and restricted cash		(13,502)	(18,654)	[1]	(4,462)	(12,354)	[1]
Cash, cash equivalents, and restricted cash, beginning of period		217,466	210,472		208,426	204,172		$ 204,172
Cash, cash equivalents, and restricted cash, end of period		$ 203,964	191,818		$ 203,964	191,818		208,426	$ 204,172
As Reported
Changes in operating assets and liabilities:
Prepaid expenses and other assets, current and noncurrent	[2]		(3,164)			(5,705)
Net cash used in operating activities			(9,523)			(982)		61,800	(1,200)
Net decrease in cash, cash equivalents, and restricted cash			(18,416)			(12,116)
Cash, cash equivalents, and restricted cash, beginning of period			183,691			177,391		177,391
Cash, cash equivalents, and restricted cash, end of period			165,275			165,275			177,391
Accounting Standards Update 2016-18
Changes in operating assets and liabilities:
Prepaid expenses and other assets, current and noncurrent	[2]		(3,402)			(5,943)
Net cash used in operating activities			(9,761)			(1,220)
Net decrease in cash, cash equivalents, and restricted cash			(18,654)			(12,354)
Cash, cash equivalents, and restricted cash, beginning of period			210,472			204,172		204,172
Cash, cash equivalents, and restricted cash, end of period			191,818			191,818			204,172
Accounting Standards Update 2016-18 | Adjustments
Changes in operating assets and liabilities:
Prepaid expenses and other assets, current and noncurrent	[2]		(238)			(238)
Net cash used in operating activities			(238)			(238)		35,400	(2,400)
Net decrease in cash, cash equivalents, and restricted cash			(238)			(238)
Cash, cash equivalents, and restricted cash, beginning of period			26,781			26,781		$ 26,781
Cash, cash equivalents, and restricted cash, end of period			$ 26,543			$ 26,543			$ 26,781

[1] Adjusted due to the adoption of ASU 2016-18

[2] Changes in restricted cash were included as part of prepaid expenses and other assets, current and noncurrent.