Credit Facilities (Summary Of Outstanding Letters Of Credit And/Or Borrowings Of Citibank Holdings Credit Facility) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Line of Credit Facility [Line Items]
Commitment	$ 1,250,000
Citibank Holdings Credit Facility [Member]
Line of Credit Facility [Line Items]
Commitment	150,000	150,000
In Use
Revolving Credit Borrowings [Member]
Line of Credit Facility [Line Items]
In Use
Holdings Letters Of Credit [Member]
Line of Credit Facility [Line Items]
In Use	851	851
Date of Expiry	Dec. 31, 2014	Dec. 31, 2014
Citibank Holdings Credit Facility [Member]
Line of Credit Facility [Line Items]
Commitment	150,000	150,000
In Use	$ 851	$ 851