Financing Arrangement (Line of Credit Facility) (Details) (USD $)
In Millions, unless otherwise specified
1 Months Ended 60 Months Ended
Aug. 30, 2012
Mar. 19, 2020
Line of Credit Facility [Line Items]    
Line of Credit Facility, Initiation Date   Mar. 19, 2015
Line of Credit Facility, Expiration Date Feb. 29, 2016 Mar. 19, 2020
Revolving Credit Facility [Member]    
Line of Credit Facility [Line Items]    
Line of Credit Facility, Maximum Borrowing Capacity 500 500
Option To Request Additional Commitments On Credit Facility   250
Debt Instrument, Fee Amount   2
LineofCreditFacilityTerm1   5 years