Summary of Significant Accounting Policies - Recent Accounting Pronouncements (Details) - USD ($) $ in Millions |
Jan. 01, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
---|---|---|---|---|
New Accounting Pronouncements or Change in Accounting Principle [Line Items] | ||||
Total assets | $ 12,914.2 | $ 12,280.6 | $ 9,973.0 | |
Total liabilities | $ 10,077.9 | $ 9,331.6 | ||
Accounting Standards Update 2016-02 | Scenario, Forecast | Minimum | ||||
New Accounting Pronouncements or Change in Accounting Principle [Line Items] | ||||
Total assets | $ 200.0 | |||
Total liabilities | 270.0 | |||
Accounting Standards Update 2016-02 | Scenario, Forecast | Maximum | ||||
New Accounting Pronouncements or Change in Accounting Principle [Line Items] | ||||
Total assets | 250.0 | |||
Total liabilities | $ 320.0 |