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Stock-based Compensation Narrative - Stock Options (Details) - USD ($) $ / shares in Units, $ in Millions		6 Months Ended
	Jul. 27, 2016	Jun. 30, 2019	Jun. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value of options exercised		$ 3.4	$ 1.4
Weighted average exercise price, granted		$ 0
Compensation not yet recognized		$ 0.7
Stock option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average exercise price, granted	$ 16.00
Weighted average grant date fair value	$ 2.71
Contractual term	10 years
Vesting period	4 years
Compensation cost not yet recognized, period		1 year 1 month 6 days