Annual report pursuant to Section 13 and 15(d)

401(k) Plan (Details)

v3.10.0.1
401(k) Plan (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Defined Contribution Plan [Abstract]      
Defined contribution plan expense $ 5.9 $ 6.2 $ 6.3