Stockholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	$ 1,167,820	$ 1,087,217	$ 1,189,009	$ 1,120,689
Equity awards exercised/vested, net			116	56
Share-based compensation expense	4,308	5,436	13,657	14,876
Taxes paid for net share settlements	(1,001)	(3,745)	(8,367)	(4,843)
Other comprehensive loss (gain), net	(6,212)	(1,979)	(7,866)	(10,044)
Repurchases of common stock			(35,216)
Other comprehensive gain (loss), net		(1,978)		(10,082)
Net income	95,387	94,025	118,549	113,987
Balance at end of period	1,260,302	1,180,955	1,260,302	1,180,955
ASU 2016-02
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of adoption of ASC			(9,580)
ASU 2014-09
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of adoption of ASC				(53,728)
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	264	263	264	245
Equity awards exercised/vested, net		1		19
Balance at end of period	264	264	264	264
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	456,195	460,000	464,112	451,844
Equity awards exercised/vested, net	(2,224)	(234)	(12,124)	(383)
Share-based compensation expense	4,308	5,436	13,657	14,876
Taxes paid for net share settlements	(1,001)	(3,745)	(8,367)	(4,843)
Other comprehensive gain (loss), net				(37)
Balance at end of period	457,278	461,457	457,278	461,457
Accumulated Other Comprehensive Loss
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	(16,848)	(13,587)	(15,194)	(5,522)
Other comprehensive loss (gain), net	(6,212)		(7,866)
Other comprehensive gain (loss), net		(1,979)		(10,044)
Balance at end of period	(23,060)	(15,566)	(23,060)	(15,566)
Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	772,463	640,774	758,881	674,542
Other comprehensive gain (loss), net		1		(1)
Net income	95,387	94,025	118,549	113,987
Balance at end of period	867,850	734,800	867,850	734,800
Retained Earnings | ASU 2016-02
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of adoption of ASC			(9,580)
Retained Earnings | ASU 2014-09
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of adoption of ASC				(53,728)
Common Stock Held in Treasury
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Balance at beginning of period	(44,254)	(233)	(19,054)	(420)
Equity awards exercised/vested, net	2,224	$ 233	12,240	$ 420
Repurchases of common stock			(35,216)
Balance at end of period	$ (42,030)		$ (42,030)