Fair value measurements (Tables)

9 Months Ended

Sep. 30, 2014

Fair Value Disclosures [Abstract]

Schedule of fair value of assets and liabilities measured at fair value on a recurring basis by level within the fair value hierarchy

The following tables set forth the assets and liabilities that we measure at fair value on a recurring basis by level within the fair value hierarchy as of September 30, 2014, and December 31, 2013 (in thousands):

			September 30, 2014
Description	Total		Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
Assets:
“Available-for-sale” securities	$	30,817	$	30,817	$	—	$	—
Interest rate swap agreements	$	958	$	—	$	958	$	—
Liabilities:
Interest rate swap agreements	$	1,245	$	—	$	1,245	$	—

			December 31, 2013
Description	Total		Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
Assets:
“Available-for-sale” securities	$	4,469	$	4,469	$	—	$	—
Interest rate swap agreements	$	2,870	$	—	$	2,870	$	—
Liabilities:
Interest rate swap agreements	$	6,191	$	—	$	6,191	$	—

Schedule of the book and fair values of our marketable securities, interest rate swap agreements, secured notes payable, unsecured senior notes payable, unsecured senior line of credit, and unsecured senior bank term loan

As of September 30, 2014, and December 31, 2013, the book and fair values of our “available-for-sale” marketable equity securities, interest rate swap agreements, secured notes payable, unsecured senior notes payable, unsecured senior line of credit, and unsecured senior bank term loans were as follows (in thousands):

	September 30, 2014				December 31, 2013
	Book Value		Fair Value		Book Value		Fair Value
Assets:
“Available-for-sale” marketable equity securities	$	30,817	$	30,817	$	4,469	$	4,469
Interest rate swap agreements	$	958	$	958	$	2,870	$	2,870
Liabilities:
Interest rate swap agreements	$	1,245	$	1,245	$	6,191	$	6,191
Secured notes payable	$	636,825	$	686,388	$	708,831	$	736,772
Unsecured senior notes payable	$	1,747,290	$	1,775,990	$	1,048,230	$	1,043,125
Unsecured senior line of credit	$	142,000	$	141,881	$	204,000	$	193,714
Unsecured senior bank term loans	$	975,000	$	974,424	$	1,100,000	$	1,099,897