Derivative Financial Instruments (Gains (Losses) of Fair Value Hedges Recognized as Interest Expense) (Details) - Fair Value Hedges - Qualifying Hedges - Interest Expense - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Recognized on Derivatives
Derivative Instruments, Gain (Loss) [Line Items]
Net recognized on fair value hedges (No ineffectiveness)	$ 6.1	$ 1.0
Recognized on Hedged Item
Derivative Instruments, Gain (Loss) [Line Items]
Net recognized on fair value hedges (No ineffectiveness)	$ (6.1)	$ (1.0)

Total amount of gain (loss) derived from fair value hedges recognized in earnings in the period.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624171-113959

Name:	us-gaap_GainLossOnFairValueHedgesRecognizedInEarnings
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration