Fair Value Measurements (Level 3 Significant Unobservable Inputs) (Details) $ in Millions	Sep. 30, 2019 USD ($) year	Dec. 31, 2018 USD ($) year
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability	$ 718.8	$ 592.1
Swap | Fair Value, Measurements, Recurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability	$ 37.7	$ 32.8
Swap | Visa Class A Appreciation | Fair Value, Measurements, Recurring | Level 3 | Lower Limit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	0.070	0.070
Swap | Visa Class A Appreciation | Fair Value, Measurements, Recurring | Level 3 | Upper Limit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	0.110	0.110
Swap | Conversion Rate | Fair Value, Measurements, Recurring | Level 3 | Lower Limit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	0.0162	0.0162
Swap | Conversion Rate | Fair Value, Measurements, Recurring | Level 3 | Upper Limit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	0.0164	0.0164
Swap | Expected Duration | Fair Value, Measurements, Recurring | Level 3 | Lower Limit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input	1.25	1.5
Swap | Expected Duration | Fair Value, Measurements, Recurring | Level 3 | Upper Limit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liability, measurement input | year	3.25	4.0