Accounting Policies (Details) - USD ($) $ in Millions |
9 Months Ended | ||
---|---|---|---|
Sep. 30, 2018 |
Sep. 30, 2017 |
Jan. 01, 2018 |
|
New Accounting Pronouncements or Change in Accounting Principle [Line Items] | |||
Unrealized Gain on Securities | $ 70.0 | ||
Impairment charges on privately-held investments | 3.7 | ||
Net change in cash, cash equivalents and restricted cash | $ 1,123.7 | $ (277.0) | |
Accounting Standards Update 2018-02 [Member] | |||
New Accounting Pronouncements or Change in Accounting Principle [Line Items] | |||
Cumulative Effect of New Accounting Principle in Period of Adoption | $ 3.8 | ||
Accounting Standards Update 2014-09 [Member] | |||
New Accounting Pronouncements or Change in Accounting Principle [Line Items] | |||
Cumulative Effect of New Accounting Principle in Period of Adoption | $ 8.7 |