Stockholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended
	Apr. 30, 2020	Apr. 30, 2019
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	$ 1,290,672	$ 1,189,009
Equity awards exercised/vested, net		40
Share-based compensation expense	(811)	4,227
Taxes paid for net share settlements	(306)	(5,686)
Other comprehensive loss, net	(4,026)	(3,227)
Net income (loss)	(39,295)	12,043
Balance at end of period	1,246,234	1,186,826
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	264	264
Balance at end of period	264	264
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	452,142	464,112
Equity awards exercised/vested, net	(1,185)	(5,818)
Share-based compensation expense	(811)	4,227
Taxes paid for net share settlements	(306)	(5,686)
Balance at end of period	449,840	456,835
Accumulated Other Comprehensive Loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	(18,008)	(15,194)
Other comprehensive loss, net	(4,026)	(3,227)
Balance at end of period	(22,034)	(18,421)
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	893,138	758,881
Net income (loss)	(39,295)	12,043
Balance at end of period	853,843	761,344
Common Stock Held in Treasury
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	(36,864)	(19,054)
Equity awards exercised/vested, net	1,185	5,858
Balance at end of period	$ (35,679)	$ (13,196)