Fair Value of Assets and Liabilities (Tables)

6 Months Ended

Jun. 30, 2011

Fair Value of Assets and Liabilities

Schedule of assets and liabilities measured at fair value

The table below presents certain of our assets and liabilities measured at fair value during 2011, categorized by the level of inputs used in the valuation of each asset and liability:

				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)	$	(9,030	)	$	—	$	(9,030	)	$	—

(1)       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 June 30, 2011, 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.

Fair value and carrying value of financial instruments

	June 30, 2011				December 31, 2010
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Equity investment in GOV	$	163,669	$	268,849	$	166,388	$	266,561
Senior notes and mortgage notes payable	$	2,492,769	$	2,699,814	$	2,462,847	$	2,599,075