7. Notes Payable

The following is a summary of our indebtedness:



(in millions)	September 30, 2015		December 31, 2014
Commercial banks
Unsecured credit facility	$	200.0	$	—
Unsecured short-term borrowings	23.0		—
	$	223.0	$	—

Senior unsecured notes
5.08% Notes, due 2015	$	—	$	249.9
5.75% Notes, due 2017	246.6		246.5
4.70% Notes, due 2021	249.1		249.0
3.07% Notes, due 2022	347.2		347.0
5.00% Notes, due 2023	248.0		247.8
4.27% Notes, due 2024	249.6		249.6
3.59% Notes, due 2024	248.2		248.1
	$	1,588.7	$	1,837.9

Total unsecured notes payable	1,811.7		1,837.9

Secured notes
0.95% – 5.63% Conventional Mortgage Notes, due 2018 – 2045	870.0		870.9
Tax-exempt Mortgage Note, due 2028 (1.24% floating rate)	33.5		34.7
	903.5		905.6
Total notes payable	$	2,715.2	$	2,743.5

Other floating rate debt included in secured notes (0.95%)	$	175.0	$	175.0

In August 2015, we amended our $500 million unsecured credit facility to extend the maturity date from September 2015 to August 2019, with two six-month options to extend at our election to August 2020, and increased the facility from $500 million to $600 million, with the option to further increase it to $900 million by either adding additional banks to the facility or obtaining the agreement of the existing banks to increase their commitments. The interest rate on this credit facility is based upon the London Interbank Offered Rate ("LIBOR") plus a margin which is subject to change as our credit ratings change. Advances under this credit facility 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 $300 million or the remaining amount available under the credit facility. This credit facility is subject to customary financial covenants and limitations. We believe we are in compliance with all such financial covenants and limitations on the date of this filing.

Our credit facility provides us with the ability to issue up to $50 million in letters of credit. While our issuance of letters of credit does not increase our borrowings outstanding under our credit facility, it does reduce the amount available. At September 30, 2015, we had approximately $200.0 million outstanding on our credit facility and we had outstanding letters of credit totaling approximately $10.1 million, leaving approximately $389.9 million available under our credit facility.

In May 2015, we entered into a $40 million unsecured short-term borrowing facility which matures in May 2016. The interest rate is based upon LIBOR plus 1.05%. At September 30, 2015, we had approximately $23.0 million outstanding on this unsecured short-term borrowing facility.

In June 2015, we used cash and borrowings from our existing unsecured credit facility to repay the principal amount of our 5.08% senior unsecured notes payable, which was scheduled to mature on June 15, 2015, for a total of $250.0 million, plus accrued interest.

At September 30, 2015 and 2014, we had outstanding floating rate debt of approximately $431.5 million and $210.1 million, respectively, which included our unsecured credit facility and short-term borrowings, and the weighted average interest rate on such debt was approximately 1.0% for each of the nine months ended September 30, 2015 and 2014.

Our indebtedness, which includes our unsecured credit facility and unsecured short-term borrowings, had a weighted average maturity of approximately 6.0 years at September 30, 2015. The table below is a summary of the maturity dates of our outstanding debt and principal amortizations, and the weighted average interest rates on such debt, at September 30, 2015:



(in millions)	Amount		Weighted Average Interest Rate
2015 (1)	$	0.5	—	%
2016 (2)	25.0		1.3
2017	249.0		5.8
2018	177.4		0.9
2019 (3)	846.5		4.3
Thereafter	1,416.8		4.0
Total	$	2,715.2	4.0	%


(1)	Includes only scheduled principal amortizations.

(2) Includes $23.0 million of unsecured short-term borrowings.


(3)	Includes $200.0 million balance outstanding under our unsecured credit facility.