Annual report pursuant to Section 13 and 15(d)

Summary of Significant Accounting Policies - Long-Lived Assets (Details)

v3.19.1
Summary of Significant Accounting Policies - Long-Lived Assets (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Accounting Policies [Abstract]      
Impairment of long-lived assets $ 4.3 $ 4.1 $ 1.9