Credit Facilities (Tables)

12 Months Ended

Dec. 31, 2015

Line of Credit Facility [Line Items]

Summary Of Costs Incurred Connection With Credit Facilities

	Years Ended December 31,
(Dollars in thousands)	2015		2014		2013
Credit facility fees incurred	$	756	$	659	$	964

Wells Fargo Bank Group Credit Facility [Member]

Line of Credit Facility [Line Items]

Summary Of Outstanding Letters Of Credit And/Or Borrowings

(Dollars in thousands)		At December 31, 2015					At December 31, 2014
Bank		Commitment		In Use		Date of Expiry	Commitment		In Use		Date of Expiry
Wells Fargo Bank Group Credit Facility	Tranche One	$	200,000	$	-		$	200,000	$	-
Tranche Two			600,000		2,488	12/12/2016		600,000		444,012	12/31/2015
			-		447,178	12/31/2016		-		-
Total Wells Fargo Bank Group Credit Facility		$	800,000	$	449,666		$	800,000	$	444,012

Citibank Bilateral Agreement [Member]

Line of Credit Facility [Line Items]

Summary Of Outstanding Letters Of Credit And/Or Borrowings

(Dollars in thousands)	At December 31, 2015					At December 31, 2014
Bank	Commitment		In Use		Date of Expiry	Commitment		In Use		Date of Expiry
Citibank Bilateral Letter of Credit Agreement	$	300,000	$	3,672	11/24/2016	$	300,000	$	112	8/30/2015
				67,783	12/31/2016				3,672	11/24/2015
				179	8/30/2017				70,922	12/31/2015
				316	12/31/2017				2,014	12/31/2016
				99,521	12/31/2019				149,353	12/30/2018
Total Citibank Bilateral Agreement	$	300,000	$	171,471		$	300,000	$	226,073

Lloyd's of London Bank Credit Facility [Member]

Line of Credit Facility [Line Items]

Summary Of Outstanding Letters Of Credit And/Or Borrowings

(Dollars in thousands)	At December 31, 2015					At December 31, 2014
Bank	Commitment		In Use		Date of Expiry	Commitment		In Use		Date of Expiry
Lloyd's Bank plc	£	175,000	£	164,961	12/31/2019	£	-	£	-
		-		-			-		-
Total Lloyd's Bank Credit Facility	£	175,000	£	164,961		£	-	£	-