Fair Value Measurements (Narrative) (Details) $ in Millions	Sep. 30, 2020 USD ($)
Not Designated as Hedging Instrument
Debt Instrument [Line Items]
Fair value of net derivative liability position	$ 1
Senior Notes \| 4.20% Senior Notes Due March 2022
Debt Instrument [Line Items]
Stated interest rate	4.10%

Contractual interest rate for funds borrowed, under the debt agreement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant