Indebtedness

6 Months Ended

Jun. 30, 2018

All debt is issued directly or indirectly by the Partnership. The General Partner does not have any indebtedness, but does guarantee some of the unsecured debt of the Partnership. The following table summarizes the book value and changes in the fair value of our debt (in thousands):



	Book Value at 12/31/2017		Book Value at 6/30/2018		Fair Value at 12/31/2017		Payments/Payoffs			Adjustments to Fair Value			Fair Value at 6/30/2018
Fixed rate secured debt	$	309,463	$	303,867	$	325,753	$	(5,557	)	$	(3,638	)	$	316,558
Variable rate secured debt	2,500		2,500		2,500		—			—			2,500
Unsecured debt	2,132,042		2,130,720		2,190,548		(1,322		)	(85,261		)	2,103,965
Total	$	2,444,005	$	2,437,087	$	2,518,801	$	(6,879	)	$	(88,899	)	$	2,423,023
Less: Deferred financing costs	21,114		19,658
Total indebtedness as reported on the consolidated balance sheets	$	2,422,891	$	2,417,429

Secured Debt

Because our fixed rate secured debt is not actively traded in any marketplace, we utilized a discounted cash flow methodology to determine its fair value. Accordingly, we calculated fair value by applying an estimate of the current market rate to discount the debt's remaining contractual cash flows. Our estimate of a current market rate, which is the most significant input in the discounted cash flow calculation, is intended to replicate debt of similar maturity and loan-to-value relationship. The estimated rates ranged from 3.90% to 4.20%, depending on the attributes of the specific loans. The current market rates we utilized were internally estimated; therefore, we have concluded that our determination of fair value for our fixed rate secured debt was primarily based upon level 3 inputs.

During the six months ended June 30, 2018, we paid $3.2 million on fixed rate secured loans, which had a weighted average stated interest rate of 7.43%.

Unsecured Debt

At June 30, 2018, all of our unsecured debt bore interest at fixed rates and primarily consisted of unsecured notes that are publicly traded. We utilized broker estimates in estimating the fair value of our fixed rate unsecured debt. Our unsecured notes are thinly traded and, in certain cases, the broker estimates were not based upon comparable transactions. The broker estimates took into account any recent trades within the same series of our fixed rate unsecured debt, comparisons to recent trades of other series of our fixed rate unsecured debt, trades of fixed rate unsecured debt from companies with profiles similar to ours, as well as overall economic conditions. We reviewed these broker estimates for reasonableness and accuracy, considering whether the estimates were based upon market participant assumptions within the principal and most advantageous market and whether any other observable inputs would be more accurate indicators of fair value than the broker estimates. We concluded that the broker estimates were representative of fair value. We have determined that our estimation of the fair value of our fixed rate unsecured debt was primarily based upon level 3 inputs. The estimated trading values of our fixed rate unsecured debt, depending on the maturity and coupon rates, ranged from 93.00% to 121.00% of face value.

The indentures (and related supplemental indentures) governing our outstanding series of unsecured notes also require us to comply with financial ratios and other covenants regarding our operations. We were in compliance with all such financial covenants at June 30, 2018.

Unsecured Line of Credit

Our unsecured line of credit at June 30, 2018 is described as follows (in thousands):



Description	Borrowing Capacity		Maturity Date	Outstanding Balance at June 30, 2018
Unsecured Line of Credit - Partnership	$	1,200,000	January 30, 2022	$	—

The Partnership's unsecured line of credit has an interest rate on borrowings of LIBOR plus 0.875% and has a maturity date of January 30, 2022, with options to extend until January 30, 2023. Subject to certain conditions, the terms also include an option to increase the facility by up to an additional $800.0 million, for a total of up to $2.00 billion. This line of credit provides us with an option to obtain borrowings from financial institutions that participate in the line at rates that may be lower than the stated interest rate, subject to certain restrictions.

This line of credit contains financial covenants that require us to meet certain financial ratios and defined levels of performance, including those related to fixed charge coverage, unsecured interest expense coverage and debt-to-asset value (with asset value being defined in the Partnership's unsecured line of credit agreement). At June 30, 2018, we were in compliance with all financial covenants under this line of credit.

To the extent there are outstanding borrowings, we utilize a discounted cash flow methodology in order to estimate the fair value of outstanding borrowings on our unsecured line of credit. To the extent that credit spreads have changed since the origination of the line of credit, the net present value of the difference between future contractual interest payments and future interest payments based on our estimate of a current market rate would represent the difference between the book value and the fair value. Our estimate of a current market rate is based upon the rate, considering current market conditions and our specific credit profile, at which we estimate we could obtain similar borrowings. As our credit spreads have not changed appreciably, we believe that the contractual interest rate and the current market rate on the line of credit are the same. The current market rate is internally estimated and therefore is primarily based upon a level 3 input.