Credit Facilities (Summary Of Outstanding Letters Of Credit And/Or Borrowings Of Citibank Holdings Credit Facility) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Line of Credit Facility [Line Items]
Commitment	$ 1,100,000
Citibank Holdings Credit Facility [Member]
Line of Credit Facility [Line Items]
Commitment		150,000
Revolving Credit Borrowings [Member]
Line of Credit Facility [Line Items]
Commitment
In Use
Citibank Holdings Credit Facility [Member]
Line of Credit Facility [Line Items]
Commitment		150,000
In Use		851
Date of Loan	Aug. 15, 2011
Date of Expiry	Aug. 15, 2014
Holdings Letters Of Credit [Member]
Line of Credit Facility [Line Items]
In Use		$ 851
Date of Expiry		Dec. 31, 2014