Borrowings Under Lines of Credit Arrangements and Related Items (Tables)

12 Months Ended

Dec. 31, 2012

Borrowings Under Line of Credit Arrangement and Related Items (Tables) [Abstract]

Aggregate borrowings under the unsecured lines of credit arrangements

The following information relates to aggregate borrowings under our unsecured lines of credit arrangements for the periods presented (dollars in thousands):

		Year Ended December 31,
		2012		2011		2010
Balance outstanding at year end		$	0	$	610,000	$	300,000
Maximum amount outstanding at any month end		$	897,000	$	710,000	$	560,000
Average amount outstanding (total of daily
	principal balances divided by days in period)	$	191,378	$	240,104	$	268,762
Weighted-average interest rate (actual interest
	expense divided by average borrowings outstanding)		1.80%		1.51%		1.48%