Summary of Significant Accounting Policies - Net AWI Investments (Details)
$ in Millions
|12 Months Ended|
Dec. 31, 2018
|Organization, Consolidation and Presentation of Financial Statements [Abstract]|
|Adjustments related to tax attributes assumed upon spin-off||$ 0.7|
Related Party Transaction, Adjustments to Tax Attributes Assumed from Related Party
No definition available.