The valuation of financial instruments requires the Company to make estimates and judgments that affect the fair value of the instruments. The Company, where possible, bases the fair values of its financial instruments, including its derivative instruments, on listed market prices and third party quotes. Where these are not available, the Company bases its estimates on current instruments with similar terms and maturities or on other factors relevant to the financial instruments.

In the normal course of business, the Company is exposed to the effect of interest rate changes. The Company seeks to manage these risks by following established risk management policies and procedures including the use of derivatives to hedge interest rate risk on debt instruments. The Company may also use derivatives to manage commodity prices in the daily operations of the business.

A three-level valuation hierarchy exists for disclosure of fair value measurements. The valuation hierarchy is based upon the transparency of inputs to the valuation of an asset or liability as of the measurement date. A financial instrument’s categorization within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. The three levels are defined as follows:

The Company’s derivative positions are valued using models developed by the respective counterparty as well as models applied internally by the Company that use as their inputs readily observable market parameters (such as forward yield curves and credit default swap data). Employee holdings other than Common Shares within the supplemental executive retirement plan (the “SERP”) are valued using quoted market prices for identical assets and are included in other assets and other liabilities on the consolidated balance sheets. Redeemable Noncontrolling Interests – Operating Partnership/Redeemable Limited Partners are valued using the quoted market price of Common Shares. The fair values disclosed for mortgage notes payable and unsecured debt (including its commercial paper and line of credit, if applicable) were calculated using indicative rates provided by lenders of similar loans in the case of mortgage notes payable and the private unsecured debt (including its commercial paper and line of credit, if applicable) and quoted market prices for each underlying issuance in the case of the public unsecured notes.

The fair values of the Company’s financial instruments (other than mortgage notes payable, unsecured notes, commercial paper, line of credit and derivative instruments), including cash and cash equivalents and other financial instruments, approximate their carrying or contract value. The following table provides a summary of the carrying and fair values for the Company’s mortgage notes payable and unsecured debt (including its commercial paper and line of credit, if applicable) at June 30, 2019 and December 31, 2018, respectively (amounts in thousands):

	June 30, 2019				December 31, 2018
	Carrying Value		Estimated Fair Value (Level 2)		Carrying Value		Estimated Fair Value (Level 2)
Mortgage notes payable, net	$	2,599,013	$	2,602,782	$	2,385,470	$	2,352,502
Unsecured debt, net		6,531,408		6,968,724		6,432,469		6,481,426
Total debt, net	$	9,130,421	$	9,571,506	$	8,817,939	$	8,833,928

The following table summarizes the Company’s consolidated derivative instruments at June 30, 2019 (dollar amounts are in thousands):

The following tables provide a summary of the fair value measurements for each major category of assets and liabilities measured at fair value on a recurring basis and the location within the accompanying consolidated balance sheets at June 30, 2019 and December 31, 2018, respectively (amounts in thousands):

				Fair Value Measurements at Reporting Date Using
Description	Balance Sheet Location	6/30/2019		Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets
Supplemental Executive Retirement Plan	Other Assets	$	145,577	$	145,577	$	—	$	—
Total		$	145,577	$	145,577	$	—	$	—

Liabilities
Derivatives designated as hedging instruments:
Interest Rate Contracts:
Fair Value Hedges	Other Liabilities	$	24	$	—	$	24	$	—
Supplemental Executive Retirement Plan	Other Liabilities		145,577		145,577		—		—
Total		$	145,601	$	145,577	$	24	$	—

Redeemable Noncontrolling Interests –
Operating Partnership/Redeemable
Limited Partners	Mezzanine	$	436,035	$	—	$	436,035	$	—

				Fair Value Measurements at Reporting Date Using
Description	Balance Sheet Location	12/31/2018		Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets
Derivatives designated as hedging instruments:
Interest Rate Contracts:
Forward Starting Swaps	Other Assets	$	2,000	$	—	$	2,000	$	—
Supplemental Executive Retirement Plan	Other Assets		134,088		134,088		—		—
Total		$	136,088	$	134,088	$	2,000	$	—

Liabilities
Derivatives designated as hedging instruments:
Interest Rate Contracts:
Fair Value Hedges	Other Liabilities	$	2,277	$	—	$	2,277	$	—
Forward Starting Swaps	Other Liabilities		9,851		—		9,851		—
Supplemental Executive Retirement Plan	Other Liabilities		134,088		134,088		—		—
Total		$	146,216	$	134,088	$	12,128	$	—

Redeemable Noncontrolling Interests –
Operating Partnership/Redeemable
Limited Partners	Mezzanine	$	379,106	$	—	$	379,106	$	—

The following tables provide a summary of the effect of fair value hedges on the Company’s accompanying consolidated statements of operations and comprehensive income for the six months ended June 30, 2019 and 2018, respectively (amounts in thousands):

June 30, 2019 Type of Fair Value Hedge	Location of Gain/(Loss) Recognized in Income on Derivative	Amount of Gain/(Loss) Recognized in Income on Derivative		Hedged Item	Income Statement Location of Hedged Item Gain/(Loss)	Amount of Gain/(Loss) Recognized in Income on Hedged Item
Derivatives designated as hedging instruments:
Interest Rate Contracts:
Interest Rate Swaps	Interest expense	$	2,253	Fixed rate debt	Interest expense	$	(2,253	)
Total		$	2,253			$	(2,253	)

June 30, 2018 Type of Fair Value Hedge	Location of Gain/(Loss) Recognized in Income on Derivative	Amount of Gain/(Loss) Recognized in Income on Derivative			Hedged Item	Income Statement Location of Hedged Item Gain/(Loss)	Amount of Gain/(Loss) Recognized in Income on Hedged Item
Derivatives designated as hedging instruments:
Interest Rate Contracts:
Interest Rate Swaps	Interest expense	$	(2,151	)	Fixed rate debt	Interest expense	$	2,151
Total		$	(2,151	)			$	2,151

The following tables provide a summary of the effect of cash flow hedges on the Company’s accompanying consolidated statements of operations and comprehensive income for the six months ended June 30, 2019 and 2018, respectively (amounts in thousands):

	Effective Portion						Ineffective Portion
June 30, 2018 Type of Cash Flow Hedge	Amount of Gain/(Loss) Recognized in OCI on Derivative		Location of Gain/(Loss) Reclassified from Accumulated OCI into Income	Amount of Gain/(Loss) Reclassified from Accumulated OCI into Income			Location of Gain/(Loss) Recognized in Income on Derivative	Amount of Gain/(Loss) Reclassified from Accumulated OCI into Income
Derivatives designated as hedging instruments:
Interest Rate Contracts:
Forward Starting Swaps	$	11,995	Interest expense	$	(9,307	)	N/A	$	—
Total	$	11,995		$	(9,307	)		$	—

As of June 30, 2019 and December 31, 2018, there were approximately $89.8 million and $65.0 million in deferred losses, net, included in accumulated other comprehensive income (loss), respectively, related to derivative instruments. Based on the estimated fair values of the net derivative instruments at June 30, 2019, the Company may recognize an estimated $25.7 million of accumulated other comprehensive income (loss) as additional interest expense during the twelve months ending June 30, 2020.

In June 2019, the Company paid approximately $41.8 million to settle ten forward starting swaps in conjunction with the issuance of $600.0 million of ten-year unsecured public notes. The accrued interest of approximately $0.2 million was recorded as an increase to interest expense. The remaining $41.6 million will be deferred as a component of accumulated other comprehensive income (loss) and will be recognized as an increase to interest expense over the first nine years and eleven months of the notes.