Summary of Business Organization, Operations and Significant Accounting Policies - Accounting Standards Implementation (Details) - Subsequent Event - Accounting Standards Update 2016-02 $ in Millions	Jan. 01, 2019 USD ($)
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use asset	$ 135
Short-term lease liability	37
Long-term lease liability	100
Maximum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use asset	140
Short-term lease liability	42
Long-term lease liability	$ 105