Summary of Significant Accounting Policies - ASU Pronouncement Impacts (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Accounting Standards Update 2016-02 [Member] | Minimum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of new accounting principle	$ 65.0
Accounting Standards Update 2016-02 [Member] | Maximum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of new accounting principle	$ 85.0
Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of new accounting principle		$ 10.9
Accounting Standards Update 2016-16 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative effect of new accounting principle		$ 0.8