Debt (Terms Of The Senior Credit Agreement) (Narrative) (Details) - Senior Credit Agreement [Member]	12 Months Ended
	Dec. 31, 2017 item
Debt Instrument [Line Items]
Debt to annualized borrower EBITDA ratio	6.5
Debt and net hedge exposure to annualized borrower EBITDA	6.5
Consecutive trading days	30
Annualized borrower EBITDA to annualized cash interest expense	2.0