XML 79 R63.htm IDEA: XBRL DOCUMENT v3.10.0.1
Retirement Plan (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Retirement Benefits [Abstract]      
Employer matching contribution, percent of match 100.00% 100.00%  
Employer matching contribution, percent of employees' gross pay 4.00% 3.00%  
Employer contributions $ 2.2 $ 0.8 $ 0.6