Financing Agreements (Future Principal Payments of Long-Term Debt) (Details) $ in Millions	Sep. 30, 2019 USD ($)
Senior Unsecured 4.375% Notes due September 2027 [Member]
Debt Instrument [Line Items]
Debt Issuance Costs, Gross	$ 6.3

Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399

Name:	us-gaap_DeferredFinanceCostsGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant