Annual and transition report of foreign private issuers pursuant to Section 13 or 15(d)

Equity (Stock-based Compensation Plans) (Narrative) (Details)

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Equity (Stock-based Compensation Plans) (Narrative) (Details) - USD ($)
shares in Millions, $ in Millions
12 Months Ended
Jan. 02, 2020
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Vesting period   4 years    
Weighted average remaining contractual life   6 years 1 month 6 days    
Total intrinsic value of options exercised   $ 1.0 $ 0.6 $ 7.2
Unvested number of shares   0.4    
Unrecognized compensation cost   $ 3.9    
Weighted average period over which unrecognized compensation cost will be recognized   1 year 2 months 12 days    
Restricted Stock [Member]        
Value of equity classified RSUs vested   $ 7.4    
Unrecognized compensation cost   $ 41.6    
Weighted average period over which unrecognized compensation cost will be recognized   2 years 7 months 6 days    
Employee Stock Option [Member] | Minimum [Member]        
Expected option term     5 years 3 months 18 days 5 years 1 month 6 days
Employee Stock Option [Member] | Maximum [Member]        
Expected option term     5 years 6 months 6 years
2012 Plan [Member]        
Expected option term   10 years    
Equity Incentive Plan, shares authorized   0.9    
2012 Plan [Member] | Employee Stock Option [Member] | Minimum [Member]        
Vesting period   2 years    
2012 Plan [Member] | Employee Stock Option [Member] | Maximum [Member]        
Vesting period   4 years    
2012 Plan [Member] | Subsequent Event [Member]        
Equity Incentive Plan, number of additional shares authorized 0.5