Credit Facilities (Tables)

3 Months Ended

Mar. 31, 2016

Line of Credit Facility [Line Items]

Summary Of Costs Incurred Connection With Credit Facilities

	Three Months Ended
	March 31,
(Dollars in thousands)	2016		2015
Credit facility interest and fees incurred	$	370	$	132

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 March 31, 2016					At December 31, 2015
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	$	2,488	12/12/2016
			-		452,552	12/31/2016		-		447,178	12/31/2016
Total Wells Fargo Bank Group Credit Facility		$	800,000	$	455,040		$	800,000	$	449,666

Citibank Bilateral Agreement [Member]

Line of Credit Facility [Line Items]

Summary Of Outstanding Letters Of Credit And/Or Borrowings

(Dollars in thousands)	At March 31, 2016					At December 31, 2015
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	$	3,672	11/24/2016
				64,823	12/31/2016				67,783	12/31/2016
				4,058	2/28/2017				179	8/30/2017
				184	8/30/2017				316	12/31/2017
				2,598	12/31/2017				-		-
				96,738	3/30/2020				99,521	12/31/2019
Total Citibank Bilateral Agreement	$	300,000	$	172,073		$	300,000	$	171,471

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 March 31, 2016					At December 31, 2015
Bank	Commitment		In Use		Date of Expiry	Commitment		In Use		Date of Expiry
Lloyd's Bank plc	£	175,000	£	164,961	12/31/2019	£	175,000	£	164,961	12/31/2019
		-		-			-		-
Total Lloyd's Bank Credit Facility	£	175,000	£	164,961		£	175,000	£	164,961