Fair Value of Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2012

Fair Value of Assets and Liabilities

Schedule of assets and liabilities measured at fair value

				Fair Value at Reporting Date Using
Description	Total			Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)			Significant Unobservable Inputs (Level 3)
Recurring Fair Value Measurements:
Effective portion of interest rate contracts(1)	$	(16,624	)	$	—	$	(16,624	)	$	—
Nonrecurring Fair Value Measurements:
Properties held for sale(2)	$	129,474		$	—	$	—		$	129,474

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The fair value of our interest rate swap contracts is determined using the net discounted cash flows of the expected cash flows of each derivative based on the market based interest rate curve (level 2 inputs) and adjusted for our credit spread and the actual and estimated credit spreads of the counterparties (level 3 inputs). Although we have determined that the majority of the inputs used to value our derivatives fall within level 2 of the fair value hierarchy, the credit valuation adjustments associated with our derivatives utilize level 3 inputs, such as estimates of current credit spreads, to evaluate the likelihood of default by us and the counterparties. As of December 31, 2012, we have assessed the significance of the impact of the credit valuation adjustments on the overall valuation of our derivative positions and have determined that the credit valuation adjustments are not significant to the overall valuation of our derivatives. As a result, we have determined that our derivative valuations in their entirety are classified as level 2 inputs in the fair value hierarchy.

⁽²⁾

As of December 31, 2012, we recorded a loss on asset impairment of $2,452 for one property in our CBD Office segment, $129,802 for 31 properties in our Suburban Office segment and $36,378 for 26 properties in our Industrial & Other segment to reduce the aggregate carrying value of these properties from $298,106 to their estimated fair value less costs to sell of $129,474. We used broker information for all 58 properties (level 3 inputs) in determining the fair value of these properties. The valuation techniques and significant unobservable inputs used for our level 3 fair value measurements at December 31, 2012 were as follows:

Description	Fair Value at December 31, 2012		Valuation Techniques	Unobservable Inputs	Range
Properties held for sale on which we recognized impairment losses	$	129,474	Discounted cash flows and comparable sales	Discount rate	9% - 15%
				Exit capitalization rate	8% - 10%
				Market rent growth rate	2% - 3%

Schedule of valuation techniques and significant unobservable inputs used for level 3 fair value measurements

Description	Fair Value at December 31, 2012		Valuation Techniques	Unobservable Inputs	Range
Properties held for sale on which we recognized impairment losses	$	129,474	Discounted cash flows and comparable sales	Discount rate	9% - 15%
				Exit capitalization rate	8% - 10%
				Market rent growth rate	2% - 3%

Schedule of effects of interest rate derivatives on our consolidated statements of operations and consolidated statements of comprehensive income (loss)

	For the Years Ended December 31,
	2012			2011			2010
Balance at beginning of year	($	15,796	)	($	6,956	)	$	2,545
Amount of loss recognized in cumulative other comprehensive income		(5,790	)		(13,804	)		(14,408	)
Amount of loss reclassified from cumulative other comprehensive income into interest expense		4,962			4,964			4,907
Unrealized loss on derivative instruments		(828	)		(8,840	)		(9,501	)
Balance at end of year	($	16,624	)	($	15,796	)	($	6,956	)

Fair value and carrying value of financial instruments

	December 31, 2012				December 31, 2011
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Senior notes and mortgage notes payable	$	2,932,951	$	3,181,522	$	2,745,331	$	2,924,141