Equity impact of the value of stock that has been repurchased and retired during the period. The excess of the purchase price over par value can be charged against retained earnings (once the excess is fully allocated to additional paid in capital).

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Stockholders' Equity - Share repurchase programs (Details) - USD ($) $ in Thousands, shares in Millions	9 Months Ended
	Sep. 29, 2018	Oct. 31, 2018	Oct. 31, 2017	Jan. 31, 2017
Share Repurchase Programs
Program amount authorized to repurchase		$ 200,000	$ 100,000	$ 100,000
Number of shares repurchased and retired	0.3
Value of shares repurchased and retired	$ 24,300
Common Stock
Common Stock
Number of shares issued during the period	0.7