Interest rate swap agreements (Tables)

12 Months Ended

Dec. 31, 2013

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Outstanding interest rate hedge agreements designated as cash flow hedges of interest rate risk

We had the following outstanding interest rate swap agreements that were designated as cash flow hedges of interest rate risk as of December 31, 2013 (dollars in thousands):

Effective Date	Maturity Date	Number of Contracts	Weighted Average Interest Pay Rate (1)	Fair Value as of 12/31/13			Notional Amount in Effect as of
							12/31/13		12/31/14		12/31/15		12/31/16
December 29, 2006	March 31, 2014	1	4.99%	$	(596	)	$	50,000	$	—	$	—	$	—
November 30, 2009	March 31, 2014	2	5.02%	(1,800		)	150,000		—		—		—
December 31, 2013	December 31, 2014	2	0.98%	(3,795		)	500,000		—		—		—
December 31, 2013	March 31, 2015	2	0.23%	66			250,000		250,000		—		—
December 31, 2014	March 31, 2016	3	0.53%	658			—		500,000		500,000		—
March 31, 2016	March 31, 2017	3	1.40%	2,146			—		—		—		500,000
Total				$	(3,321	)	$	950,000	$	750,000	$	500,000	$	500,000

(1) In addition to the interest pay rate, borrowings outstanding as of December 31, 2013, under our unsecured senior bank term loans include an Applicable Margin of 1.20% and borrowings outstanding under our unsecured senior line of credit include an Applicable Margin of 1.10%.