Fair Value Measurements (Level 3 Significant Unobservable Inputs) (Details) - Fair Value, Measurements, Recurring - Level 3 - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Swaps Related to Sale of Certain Visa Class B Common Shares
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instrument, fair value liabilities	$ 28.7	$ 10.8
Swaps Related to Sale of Certain Visa Class B Common Shares | Group One
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Valuation Technique	Discounted Cash Flow	Discounted Cash Flow
Unobservable inputs	Visa Class A Appreciation	Visa Class A Appreciation
Swaps Related to Sale of Certain Visa Class B Common Shares | Group Two
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unobservable inputs	Conversion Rate	Conversion Rate
Swaps Related to Sale of Certain Visa Class B Common Shares | Group Three
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unobservable inputs	Expected Duration	Expected Duration
Swaps Related to Sale of Certain Visa Class B Common Shares | Lower Limit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instrument visa class A appreciation	9.00%	9.50%
Financial instrument conversion rate	1.63%	1.61%
Financial instrument expected conversion rate	2 years	1 year 6 months
Swaps Related to Sale of Certain Visa Class B Common Shares | Upper Limit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instrument visa class A appreciation	14.00%	15.00%
Financial instrument conversion rate	1.65%	1.65%
Financial instrument expected conversion rate	5 years	4 years 6 months
Auction Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 6.1	$ 17.1
Auction Rate | Group One
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Valuation Technique	Discounted Cash Flow	Discounted Cash Flow
Unobservable inputs	Remaining lives	Remaining lives
Auction Rate | Group Two
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Unobservable inputs	Discount rates	Discount rates
Auction Rate | Lower Limit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instrument remaining lives	2 years	5 months 1 day
Financial instrument discount rate	0.50%	0.30%
Auction Rate | Upper Limit
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial instrument remaining lives	8 years 7 months 20 days	8 years 7 months 20 days
Financial instrument discount rate	2.50%	4.40%