Fair Value of Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Schedule of Assets and Liabilities Measured at Fair Value

The table below presents certain of our assets and liabilities measured at fair value during 2018 and 2017, categorized by the level of inputs used in the valuation of each asset and liability (dollars in thousands):

			Fair Value at December 31, 2018 Using
			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
Description	Total		(Level 1)		(Level 2)		(Level 3)
Recurring Fair Value Measurements:
Marketable securities	$	249,602	$	249,602	$	—	$	—

			Fair Value at December 31, 2017 Using
			Quoted Prices in Active Markets for Identical Assets		Significant Other Observable Inputs		Significant Unobservable Inputs
Description	Total		(Level 1)		(Level 2)		(Level 3)
Recurring Fair Value Measurements:
Effective portion of interest rate cap contract	$	17	$	—	$	17	$	—
Marketable securities	$	276,928	$	276,928	$	—	$	—

Schedule of Fair Value and Carrying Value of Financial Instruments

At December 31, 2018 and 2017, the fair value of these additional financial instruments were not materially different from their carrying values, except as follows (in thousands):

	December 31, 2018				December 31, 2017
	Principal Balance		Fair Value		Principal Balance		Fair Value
Senior unsecured debt and mortgage notes payable	$	276,000	$	283,214	$	856,940	$	874,280