10.	Derivative Instruments and Hedging Activities

Interest Rate Swaps – Designated as Cash Flow Hedges

As of December 31, 2017, we had interest rate swaps with an aggregate notional amount of $1.0 billion that were designated as cash flow hedges. We also have entered into forward starting interest rate swaps with an aggregate notional amount of $400,000,000 to extend the maturity of certain swaps for an additional year. Changes in the fair value of interest rate swaps that are designated as cash flow hedges are recognized in “other comprehensive income (loss)” (outside of earnings). We recognized other comprehensive income of $10,618,000 and $8,161,000 for the years ended December 31, 2017 and 2016 and other comprehensive loss of $9,241,000 for the year ended December 31, 2015, from the changes in fair value of these interest rate swaps. See Note 11, Accumulated Other Comprehensive Income. During the next twelve months, we estimate that $223,000 of the amounts recognized in accumulated other comprehensive income (loss) will be reclassified as an increase to interest expense.

The table below summarizes the fair value of our interest rate swaps that are designated as cash flow hedges.

	Fair Value as of December 31,
	2017		2016
Interest rate swap assets designated as cash flow hedges (included in "other assets")	$	9,855	$	139

Interest rate swap liabilities designated as cash flow hedges (included in "other liabilities")	$	317	$	1,219

We have agreements with various derivative counterparties that contain provisions wherein a default on our indebtedness could be deemed a default on our derivative obligations, which would require us to either post collateral up to the fair value of our derivative obligations or settle the obligations for cash. As of December 31, 2017, we did not have any obligations relating to our swaps that contained such provisions.

Interest Rate Swaps – Non-designated Hedges

As of December 31, 2017, we did not have any interest rate swaps that were not designated as hedges. As of December 31, 2016, we had interest rate swap liabilities that had a fair value of $21,227,000, which were terminated on January 19, 2017 in connection with the refinancing of One Market Plaza. See Note 9, Debt for additional details. Changes in the fair value of interest rate swaps that are not designated as hedges are recognized in earnings. For the years ended December 31, 2017, 2016 and 2015, we recognized unrealized gains of $1,802,000, $39,814,000 and $75,760,000, respectively, from the changes in the fair value of these interest rate swaps.