In the normal course of business, our operations are exposed to market risks, including the effect of changes in foreign currency exchange rates and interest rates. We may enter into derivative financial instruments to offset these underlying market risks. See Note 2 for our derivative financial instruments policy.

The following table presents the fair value of our derivative financial instruments recognized within Other Assets and Other Liabilities on the Consolidated Balance Sheets at December 31 (in thousands):

	2019				2018
	Asset		Liability		Asset		Liability
Undesignated derivatives
Foreign currency contracts
Forwards
Brazilian real	$	181	$	49	$	80	$	-
British pound sterling		731		3,823		2,266		324
Canadian dollar		523		1,855		3,336		53
Chinese renminbi		-		81		-		-
Euro		7,135		2,034		7,895		1,922
Japanese yen		3,889		97		3,334		1,318
Mexican peso		-		-		159		-
Swedish krona		-		797		-		-

Interest rate swaps
U.S. dollar		-		-		27		-

Designated derivatives
Foreign currency contracts
Net investment hedges
Brazilian real		-		-		-		3,165
British pound sterling		807		13,189		-		949
Canadian dollar		-		1,926		5,634		-

Interest rate swaps
Cash flow hedges
Euro		-		-		-		428
Total fair value of derivatives	$	13,266	$	23,851	$	22,731	$	8,159

The following table summarizes the activity of our undesignated foreign currency contracts for the years ended December 31 (in millions, except for weighted average forward rates and number of active contracts):

	2019																				2018																		2017
	CAD			EUR			GBP			JPY			SEK		Other			Total			CAD			EUR			GBP			JPY			Other			Total			CAD			EUR			GBP			JPY			Total
Notional amounts at January 1	$	55		$	314		$	118		$	177		$	-	$	5		$	669		$	56		$	233		$	132		$	153		$	-		$	574		$	38		$	197		$	78		$	144		$	457
New contracts		201			619			1,111			85			31		524			2,571			28			252			55			102			423			860			41			143			151			75			410
Matured, expired or settled contracts		(136	)		(352	)		(1,051	)		(80	)		-		(514	)		(2,133	)		(29	)		(171	)		(69	)		(78	)		(418	)		(765	)		(23	)		(107	)		(97	)		(66	)		(293	)
Notional amounts at December 31	$	120		$	581		$	178		$	182		$	31	$	15		$	1,107		$	55		$	314		$	118		$	177		$	5		$	669		$	56		$	233		$	132		$	153		$	574

Weighted average forward rate at December 31		1.32			1.13			1.32			103.39			9.42								1.28			1.21			1.32			105.17									1.29			1.17			1.29			106.25
Active contracts at December 31		40			53			50			44			20								24			35			24			34									24			29			20			34

The following table summarizes the undesignated derivative financial instruments exercised and associated realized and unrealized gains (losses) in Foreign Currency and Derivative Gains (Losses), Net in the Consolidated Statements of Income for the years ended December 31 (in millions, except for number of exercised contracts):

The following table summarizes the activity of our foreign currency contracts designated as net investment hedges for the years ended December 31 (in millions, except for weighted average forward rates and number of active contracts):

	2019															2018														2017
	BRL			CAD			EUR			GBP			Total			BRL			CAD			EUR			GBP		Total			CAD			GBP			Total
Notional amounts at January 1	$	460		$	100		$	-		$	127		$	687		$	-		$	99		$	-		$	-	$	99		$	100		$	46		$	146
New contracts		489			97			420			649			1,655			1,568			100			1,053			127		2,848			99			127			226
Matured, expired or settled contracts		(949	)		(100	)		(420	)		(389	)		(1,858	)		(1,108	)		(99	)		(1,053	)		-		(2,260	)		(100	)		(173	)		(273	)
Notional amounts at December 31	$	-		$	97		$	-		$	387		$	484		$	460		$	100		$	-		$	127	$	687		$	99		$	-		$	99

Weighted average forward rate at December 31		-			1.32			-			1.29						3.91			1.28			-			1.28					1.34			-
Active contracts at December 31		-			2			-			5						1			2			-			2					2			-

The following table summarizes the activity of our interest rate swaps designated as cash flow hedges for the years ended December 31 (in millions):

	2019			2018											2017
	EUR			CAD			EUR		USD			Total			CAD
Notional amounts at January 1	$	500		$	271		$	-	$	-		$	271		$	271
New contracts ⁽¹⁾		-			-			500		300			800			-
Matured, expired or settled contracts ⁽¹⁾⁽²⁾		(500	)		(271	)		-		(300	)		(571	)		-
Notional amounts at December 31	$	-		$	-		$	500	$	-		$	500		$	271

The following table summarizes our debt and accrued interest, designated as a hedge of our net investment in international subsidiaries at December 31 (in millions):

The following table summarizes the unrealized gains (losses) in Foreign Currency and Derivative Gains (Losses), Net on the remeasurement of the unhedged portion of our debt and accrued interest for the years ended December 31 (in millions):

The change in Other Comprehensive Income (Loss) in the Consolidated Statements of Comprehensive Income during the periods presented was due to the translation into U.S. dollars from the consolidation of the financial statements of our consolidated subsidiaries whose functional currency is not the U.S. dollar. The change in fair value of the effective portion of our derivative financial instruments that have been designated as net investment hedges and cash flow hedges and the translation of our nonderivative financial instruments as discussed above are also included in Other Comprehensive Income (Loss).

The following table presents these changes in Other Comprehensive Income (Loss) for the years ended December 31 (in thousands):

	2019			2018			2017
Derivative net investment hedges	$	(22,600	)	$	26,457		$	(12,762	)
Nonderivative net investment hedges		141,675			151,083			(477,755	)
Cumulative translation adjustment		(20,593	)		(368,130	)		553,972
Total foreign currency translation gains (losses), net	$	98,482		$	(190,590	)	$	63,455

Cash flow hedges⁽¹⁾	$	4,665		$	(5,815	)	$	12,726
Our share of derivatives from unconsolidated co-investment ventures		(6,000	)		4,492			9,865
Total unrealized gains (losses) on derivative contracts, net	$	(1,335	)	$	(1,323	)	$	22,591
Total change in other comprehensive income (loss)	$	97,147		$	(191,913	)	$	86,046

We have estimated the fair value of our financial instruments using available market information and valuation methodologies we believe to be appropriate for these purposes. Considerable judgment and a high degree of subjectivity are involved in developing these estimates and, accordingly, they are not necessarily indicative of amounts that we would realize on disposition. See Note 2 for more information on our fair value measurements policy.

At December 31, 2019 and 2018, other than the derivatives discussed previously, we did not have any significant financial assets or financial liabilities that were measured at fair value on a recurring basis in the Consolidated Financial Statements. All of our derivatives held at December 31, 2019 and 2018 were classified as Level 2 of the fair value hierarchy.

Acquired properties and assets we expect to sell or contribute are significant nonfinancial assets that met the criteria to be measured at fair value on a nonrecurring basis, as detailed in our accounting policy in Note 2. At December 31, 2019 and 2018, we estimated the fair value of our properties using Level 2 or Level 3 inputs from the fair value hierarchy. See more information on our acquired properties in Notes 3 and 4 and assets held for sale or contribution in Note 6.

At December 31, 2019 and 2018, the carrying amounts of certain financial instruments, including cash and cash equivalents, accounts and notes receivable, accounts payable and accrued expenses were representative of their fair values.

The differences in the fair value of our debt from the carrying value in the table below were the result of differences in interest rates or borrowing spreads that were available to us at December 31, 2019 and 2018, as compared with those in effect when the debt was issued or assumed, including reduced borrowing spreads due to our improved credit ratings. The senior notes and many of the issuances of secured mortgage debt contain prepayment penalties or yield maintenance provisions that could make the cost of refinancing the debt at lower rates exceed the benefit that would be derived from doing so.

The following table reflects the carrying amounts and estimated fair values of our debt at December 31 (in thousands):

	2019				2018
	Carrying Value		Fair Value		Carrying Value		Fair Value
Credit Facilities	$	184,255	$	184,255	$	50,500	$	50,513
Senior notes		9,660,570		10,228,715		8,304,147		8,606,864
Term loans and unsecured other		1,441,882		1,463,841		1,921,428		1,946,335
Secured mortgage		619,170		651,047		813,740		849,417
Total	$	11,905,877	$	12,527,858	$	11,089,815	$	11,453,129

The fair value of the senior notes outstanding at December 31, 2019 and 2018 increased as certain issuances yielded higher interest rates than the overall bond yields available in the market, driving a larger increase in the fair value of debt year over year.