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

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

v3.8.0.1
Equity (Stock-based Compensation Plans) (Narrative) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Jan. 03, 2017
Vesting period 4 years      
Weighted average remaining contractual life 5 years 6 months      
Total intrinsic value of options exercised $ 7,200 $ 1,500 $ 4,600  
Unvested number of shares 2,200,000      
Unrecognized compensation cost $ 22,300      
Weighted average period over which unrecognized compensation cost will be recognized 2 years 10 months 25 days      
Restricted Stock [Member]        
Value of equity classified RSUs vested $ 6,800      
Unrecognized compensation cost $ 2,900      
Weighted average period over which unrecognized compensation cost will be recognized 2 years 9 months 18 days      
Employee Stock Option [Member]        
Expected option term     6 years  
2012 Plan [Member]        
Expected option term 10 years      
Equity Incentive Plan, shares authorized 1,900,000      
Increase of shares reserved       500,000
2012 Plan [Member] | Employee Stock Option [Member]        
Vesting period 4 years