9. Notes Payable

The following is a summary of our indebtedness:



	December 31,
(in millions)	2012		2011
Senior unsecured notes
5.93% Notes, due 2012	$	—	$	189.6
5.45% Notes, due 2013	199.9		199.7
5.08% Notes, due 2015	249.5		249.3
5.75% Notes, due 2017	246.3		246.2
4.70% Notes, due 2021	248.7		248.6
3.07% Notes, due 2022	346.3		—
5.00% Notes, due 2023	247.5		247.3
	1,538.2		1,380.7

Secured notes
1.02% – 6.00% Conventional Mortgage Notes, due 2013 – 2045	934.6		1,012.3
1.37% Tax-exempt Mortgage Note, due 2028	37.7		39.1
	972.3		1,051.4
Total notes payable	$	2,510.5	$	2,432.1
Floating rate tax-exempt debt included in secured notes (1.37%)	$	37.7	$	39.1
Floating rate debt included in secured notes (1.02%)	175.0		206.4
Value of real estate assets, at cost, subject to secured notes	1,584.7		1,651.0

We have a $500 million unsecured credit facility which matures in September 2015 with an option to extend at our election to September 2016. Additionally, we have the option to increase this credit facility to $750 million by either adding additional banks to the credit facility or obtaining the agreement of the existing banks in the credit facility to increase their commitments. The interest rate is based upon LIBOR plus a margin which is subject to change as our credit ratings change. Advances under the line of credit may be priced at the scheduled rates, or we may enter into bid rate loans with participating banks at rates below the scheduled rates. These bid rate loans have terms of 180 days or less and may not exceed the lesser of $250 million or the remaining amount available under the line of credit. The line of credit is subject to customary financial covenants and limitations. We are in compliance with all such financial covenants and limitations.

Our line of credit provides us with the ability to issue up to $100 million in letters of credit. While our issuance of letters of credit does not increase our borrowings outstanding under our line of credit, it does reduce the amount available. At December 31, 2012, we had no balances outstanding on our $500 million unsecured line of credit. However, we had outstanding letters of credit totaling approximately $11.0 million, leaving approximately $489.0 million available under our unsecured line of credit. As an alternative to our unsecured line of credit, from time to time we may borrow using an unsecured overnight borrowing facility. Our use of short-term borrowings does not decrease the amount available under our unsecured line of credit.

In December 2012, we issued from our existing shelf registration statement $350 million aggregate principal amount of 2.95% senior unsecured notes due December 2022 (the “2022 Notes”). The 2022 Notes were offered to the public at 98.945% of their face amount with a yield to maturity of 3.07%. We received net proceeds of approximately $343.7 million, net of underwriting discounts and other offering expenses. Interest on the 2022 Notes is payable semi-annually on June 15 and December 15, beginning June 15, 2013. We may redeem the 2022 Notes, in whole or in part, at any time at a redemption price equal to the principal amount and accrued interest of the notes being redeemed, plus a make-whole provision. If, however, we redeem the 2022 Notes 90 days or fewer prior to the maturity date, the redemption price will equal 100% of the principal amount of the 2022 Notes to be redeemed plus accrued and unpaid interest on the amount being redeemed to the redemption date. The 2022 Notes are direct, senior unsecured obligations and rank equally with all of our other unsecured and unsubordinated indebtedness. We used the proceeds from this offering, together with cash on hand, to repay our outstanding balance on our line of credit, and the remainder for general corporate purposes, which included property acquisitions and development in the ordinary course of business, capital expenditures and working capital.

At December 31, 2012 and 2011, the weighted average interest rate on our floating rate debt was approximately 1.1%.

Our indebtedness had a weighted average maturity of 7.0 years at December 31, 2012. Scheduled repayments on outstanding debt, including scheduled principal amortizations, and the weighted average interest rate on maturing debt at December 31, 2012 were as follows:



(in millions)	Amount		Weighted Average Interest Rate
2013	$	229.2	5.4	%
2014	35.4		3.2
2015	252.0		5.1
2016 (1)	2.3		—
2017	249.2		5.7
Thereafter	1,742.4		4.2
Total	$	2,510.5	4.5	%


(1)	Includes only scheduled principal amortizations.

In January 2013, we repaid a 4.95% secured conventional mortgage note which was scheduled to mature on April 1, 2013 for approximately $26.1 million.